| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | peano2nn 12279 | . . . . 5
⊢ (𝑁 ∈ ℕ → (𝑁 + 1) ∈
ℕ) | 
| 2 | 1 | nnnn0d 12589 | . . . 4
⊢ (𝑁 ∈ ℕ → (𝑁 + 1) ∈
ℕ0) | 
| 3 |  | derang.d | . . . . 5
⊢ 𝐷 = (𝑥 ∈ Fin ↦ (♯‘{𝑓 ∣ (𝑓:𝑥–1-1-onto→𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) ≠ 𝑦)})) | 
| 4 |  | subfac.n | . . . . 5
⊢ 𝑆 = (𝑛 ∈ ℕ0 ↦ (𝐷‘(1...𝑛))) | 
| 5 | 3, 4 | subfacval 35179 | . . . 4
⊢ ((𝑁 + 1) ∈ ℕ0
→ (𝑆‘(𝑁 + 1)) = (𝐷‘(1...(𝑁 + 1)))) | 
| 6 | 2, 5 | syl 17 | . . 3
⊢ (𝑁 ∈ ℕ → (𝑆‘(𝑁 + 1)) = (𝐷‘(1...(𝑁 + 1)))) | 
| 7 |  | fzfid 14015 | . . . . 5
⊢ (𝑁 ∈ ℕ →
(1...(𝑁 + 1)) ∈
Fin) | 
| 8 | 3 | derangval 35173 | . . . . 5
⊢
((1...(𝑁 + 1))
∈ Fin → (𝐷‘(1...(𝑁 + 1))) = (♯‘{𝑓 ∣ (𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)})) | 
| 9 | 7, 8 | syl 17 | . . . 4
⊢ (𝑁 ∈ ℕ → (𝐷‘(1...(𝑁 + 1))) = (♯‘{𝑓 ∣ (𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)})) | 
| 10 |  | subfacp1lem.a | . . . . 5
⊢ 𝐴 = {𝑓 ∣ (𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)} | 
| 11 | 10 | fveq2i 6908 | . . . 4
⊢
(♯‘𝐴) =
(♯‘{𝑓 ∣
(𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)}) | 
| 12 | 9, 11 | eqtr4di 2794 | . . 3
⊢ (𝑁 ∈ ℕ → (𝐷‘(1...(𝑁 + 1))) = (♯‘𝐴)) | 
| 13 |  | nnuz 12922 | . . . . . . . . . . 11
⊢ ℕ =
(ℤ≥‘1) | 
| 14 | 1, 13 | eleqtrdi 2850 | . . . . . . . . . 10
⊢ (𝑁 ∈ ℕ → (𝑁 + 1) ∈
(ℤ≥‘1)) | 
| 15 |  | eluzfz1 13572 | . . . . . . . . . 10
⊢ ((𝑁 + 1) ∈
(ℤ≥‘1) → 1 ∈ (1...(𝑁 + 1))) | 
| 16 | 14, 15 | syl 17 | . . . . . . . . 9
⊢ (𝑁 ∈ ℕ → 1 ∈
(1...(𝑁 +
1))) | 
| 17 |  | f1of 6847 | . . . . . . . . . 10
⊢ (𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) → 𝑓:(1...(𝑁 + 1))⟶(1...(𝑁 + 1))) | 
| 18 | 17 | adantr 480 | . . . . . . . . 9
⊢ ((𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦) → 𝑓:(1...(𝑁 + 1))⟶(1...(𝑁 + 1))) | 
| 19 |  | ffvelcdm 7100 | . . . . . . . . . 10
⊢ ((𝑓:(1...(𝑁 + 1))⟶(1...(𝑁 + 1)) ∧ 1 ∈ (1...(𝑁 + 1))) → (𝑓‘1) ∈ (1...(𝑁 + 1))) | 
| 20 | 19 | expcom 413 | . . . . . . . . 9
⊢ (1 ∈
(1...(𝑁 + 1)) → (𝑓:(1...(𝑁 + 1))⟶(1...(𝑁 + 1)) → (𝑓‘1) ∈ (1...(𝑁 + 1)))) | 
| 21 | 16, 18, 20 | syl2im 40 | . . . . . . . 8
⊢ (𝑁 ∈ ℕ → ((𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦) → (𝑓‘1) ∈ (1...(𝑁 + 1)))) | 
| 22 | 21 | ss2abdv 4065 | . . . . . . 7
⊢ (𝑁 ∈ ℕ → {𝑓 ∣ (𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)} ⊆ {𝑓 ∣ (𝑓‘1) ∈ (1...(𝑁 + 1))}) | 
| 23 |  | fveq1 6904 | . . . . . . . . 9
⊢ (𝑔 = 𝑓 → (𝑔‘1) = (𝑓‘1)) | 
| 24 | 23 | eleq1d 2825 | . . . . . . . 8
⊢ (𝑔 = 𝑓 → ((𝑔‘1) ∈ (1...(𝑁 + 1)) ↔ (𝑓‘1) ∈ (1...(𝑁 + 1)))) | 
| 25 | 24 | cbvabv 2811 | . . . . . . 7
⊢ {𝑔 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))} = {𝑓 ∣ (𝑓‘1) ∈ (1...(𝑁 + 1))} | 
| 26 | 22, 10, 25 | 3sstr4g 4036 | . . . . . 6
⊢ (𝑁 ∈ ℕ → 𝐴 ⊆ {𝑔 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))}) | 
| 27 |  | ssabral 4064 | . . . . . 6
⊢ (𝐴 ⊆ {𝑔 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))} ↔ ∀𝑔 ∈ 𝐴 (𝑔‘1) ∈ (1...(𝑁 + 1))) | 
| 28 | 26, 27 | sylib 218 | . . . . 5
⊢ (𝑁 ∈ ℕ →
∀𝑔 ∈ 𝐴 (𝑔‘1) ∈ (1...(𝑁 + 1))) | 
| 29 |  | rabid2 3469 | . . . . 5
⊢ (𝐴 = {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))} ↔ ∀𝑔 ∈ 𝐴 (𝑔‘1) ∈ (1...(𝑁 + 1))) | 
| 30 | 28, 29 | sylibr 234 | . . . 4
⊢ (𝑁 ∈ ℕ → 𝐴 = {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))}) | 
| 31 | 30 | fveq2d 6909 | . . 3
⊢ (𝑁 ∈ ℕ →
(♯‘𝐴) =
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))})) | 
| 32 | 6, 12, 31 | 3eqtrd 2780 | . 2
⊢ (𝑁 ∈ ℕ → (𝑆‘(𝑁 + 1)) = (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))})) | 
| 33 |  | elfz1end 13595 | . . . 4
⊢ ((𝑁 + 1) ∈ ℕ ↔
(𝑁 + 1) ∈ (1...(𝑁 + 1))) | 
| 34 | 1, 33 | sylib 218 | . . 3
⊢ (𝑁 ∈ ℕ → (𝑁 + 1) ∈ (1...(𝑁 + 1))) | 
| 35 |  | eleq1 2828 | . . . . . . 7
⊢ (𝑥 = 1 → (𝑥 ∈ (1...(𝑁 + 1)) ↔ 1 ∈ (1...(𝑁 + 1)))) | 
| 36 |  | oveq2 7440 | . . . . . . . . . . . . 13
⊢ (𝑥 = 1 → (1...𝑥) = (1...1)) | 
| 37 |  | 1z 12649 | . . . . . . . . . . . . . 14
⊢ 1 ∈
ℤ | 
| 38 |  | fzsn 13607 | . . . . . . . . . . . . . 14
⊢ (1 ∈
ℤ → (1...1) = {1}) | 
| 39 | 37, 38 | ax-mp 5 | . . . . . . . . . . . . 13
⊢ (1...1) =
{1} | 
| 40 | 36, 39 | eqtrdi 2792 | . . . . . . . . . . . 12
⊢ (𝑥 = 1 → (1...𝑥) = {1}) | 
| 41 | 40 | eleq2d 2826 | . . . . . . . . . . 11
⊢ (𝑥 = 1 → ((𝑔‘1) ∈ (1...𝑥) ↔ (𝑔‘1) ∈ {1})) | 
| 42 |  | fvex 6918 | . . . . . . . . . . . 12
⊢ (𝑔‘1) ∈
V | 
| 43 | 42 | elsn 4640 | . . . . . . . . . . 11
⊢ ((𝑔‘1) ∈ {1} ↔
(𝑔‘1) =
1) | 
| 44 | 41, 43 | bitrdi 287 | . . . . . . . . . 10
⊢ (𝑥 = 1 → ((𝑔‘1) ∈ (1...𝑥) ↔ (𝑔‘1) = 1)) | 
| 45 | 44 | rabbidv 3443 | . . . . . . . . 9
⊢ (𝑥 = 1 → {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)} = {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = 1}) | 
| 46 | 45 | fveq2d 6909 | . . . . . . . 8
⊢ (𝑥 = 1 →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = 1})) | 
| 47 |  | oveq1 7439 | . . . . . . . . . 10
⊢ (𝑥 = 1 → (𝑥 − 1) = (1 − 1)) | 
| 48 |  | 1m1e0 12339 | . . . . . . . . . 10
⊢ (1
− 1) = 0 | 
| 49 | 47, 48 | eqtrdi 2792 | . . . . . . . . 9
⊢ (𝑥 = 1 → (𝑥 − 1) = 0) | 
| 50 | 49 | oveq1d 7447 | . . . . . . . 8
⊢ (𝑥 = 1 → ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = (0 · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) | 
| 51 | 46, 50 | eqeq12d 2752 | . . . . . . 7
⊢ (𝑥 = 1 →
((♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) ↔ (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = 1}) = (0 · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) | 
| 52 | 35, 51 | imbi12d 344 | . . . . . 6
⊢ (𝑥 = 1 → ((𝑥 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) ↔ (1 ∈ (1...(𝑁 + 1)) →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) = 1}) = (0 ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))))) | 
| 53 | 52 | imbi2d 340 | . . . . 5
⊢ (𝑥 = 1 → ((𝑁 ∈ ℕ → (𝑥 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) ↔ (𝑁 ∈ ℕ → (1 ∈ (1...(𝑁 + 1)) →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) = 1}) = (0 ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))))) | 
| 54 |  | eleq1 2828 | . . . . . . 7
⊢ (𝑥 = 𝑚 → (𝑥 ∈ (1...(𝑁 + 1)) ↔ 𝑚 ∈ (1...(𝑁 + 1)))) | 
| 55 |  | oveq2 7440 | . . . . . . . . . . 11
⊢ (𝑥 = 𝑚 → (1...𝑥) = (1...𝑚)) | 
| 56 | 55 | eleq2d 2826 | . . . . . . . . . 10
⊢ (𝑥 = 𝑚 → ((𝑔‘1) ∈ (1...𝑥) ↔ (𝑔‘1) ∈ (1...𝑚))) | 
| 57 | 56 | rabbidv 3443 | . . . . . . . . 9
⊢ (𝑥 = 𝑚 → {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)} = {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) | 
| 58 | 57 | fveq2d 6909 | . . . . . . . 8
⊢ (𝑥 = 𝑚 → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)})) | 
| 59 |  | oveq1 7439 | . . . . . . . . 9
⊢ (𝑥 = 𝑚 → (𝑥 − 1) = (𝑚 − 1)) | 
| 60 | 59 | oveq1d 7447 | . . . . . . . 8
⊢ (𝑥 = 𝑚 → ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) | 
| 61 | 58, 60 | eqeq12d 2752 | . . . . . . 7
⊢ (𝑥 = 𝑚 → ((♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) ↔ (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) | 
| 62 | 54, 61 | imbi12d 344 | . . . . . 6
⊢ (𝑥 = 𝑚 → ((𝑥 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) ↔ (𝑚 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))))) | 
| 63 | 62 | imbi2d 340 | . . . . 5
⊢ (𝑥 = 𝑚 → ((𝑁 ∈ ℕ → (𝑥 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) ↔ (𝑁 ∈ ℕ → (𝑚 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))))) | 
| 64 |  | eleq1 2828 | . . . . . . 7
⊢ (𝑥 = (𝑚 + 1) → (𝑥 ∈ (1...(𝑁 + 1)) ↔ (𝑚 + 1) ∈ (1...(𝑁 + 1)))) | 
| 65 |  | oveq2 7440 | . . . . . . . . . . 11
⊢ (𝑥 = (𝑚 + 1) → (1...𝑥) = (1...(𝑚 + 1))) | 
| 66 | 65 | eleq2d 2826 | . . . . . . . . . 10
⊢ (𝑥 = (𝑚 + 1) → ((𝑔‘1) ∈ (1...𝑥) ↔ (𝑔‘1) ∈ (1...(𝑚 + 1)))) | 
| 67 | 66 | rabbidv 3443 | . . . . . . . . 9
⊢ (𝑥 = (𝑚 + 1) → {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)} = {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) | 
| 68 | 67 | fveq2d 6909 | . . . . . . . 8
⊢ (𝑥 = (𝑚 + 1) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))})) | 
| 69 |  | oveq1 7439 | . . . . . . . . 9
⊢ (𝑥 = (𝑚 + 1) → (𝑥 − 1) = ((𝑚 + 1) − 1)) | 
| 70 | 69 | oveq1d 7447 | . . . . . . . 8
⊢ (𝑥 = (𝑚 + 1) → ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) | 
| 71 | 68, 70 | eqeq12d 2752 | . . . . . . 7
⊢ (𝑥 = (𝑚 + 1) → ((♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) ↔ (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) | 
| 72 | 64, 71 | imbi12d 344 | . . . . . 6
⊢ (𝑥 = (𝑚 + 1) → ((𝑥 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) ↔ ((𝑚 + 1) ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))))) | 
| 73 | 72 | imbi2d 340 | . . . . 5
⊢ (𝑥 = (𝑚 + 1) → ((𝑁 ∈ ℕ → (𝑥 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) ↔ (𝑁 ∈ ℕ → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))))) | 
| 74 |  | eleq1 2828 | . . . . . . 7
⊢ (𝑥 = (𝑁 + 1) → (𝑥 ∈ (1...(𝑁 + 1)) ↔ (𝑁 + 1) ∈ (1...(𝑁 + 1)))) | 
| 75 |  | oveq2 7440 | . . . . . . . . . . 11
⊢ (𝑥 = (𝑁 + 1) → (1...𝑥) = (1...(𝑁 + 1))) | 
| 76 | 75 | eleq2d 2826 | . . . . . . . . . 10
⊢ (𝑥 = (𝑁 + 1) → ((𝑔‘1) ∈ (1...𝑥) ↔ (𝑔‘1) ∈ (1...(𝑁 + 1)))) | 
| 77 | 76 | rabbidv 3443 | . . . . . . . . 9
⊢ (𝑥 = (𝑁 + 1) → {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)} = {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))}) | 
| 78 | 77 | fveq2d 6909 | . . . . . . . 8
⊢ (𝑥 = (𝑁 + 1) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))})) | 
| 79 |  | oveq1 7439 | . . . . . . . . 9
⊢ (𝑥 = (𝑁 + 1) → (𝑥 − 1) = ((𝑁 + 1) − 1)) | 
| 80 | 79 | oveq1d 7447 | . . . . . . . 8
⊢ (𝑥 = (𝑁 + 1) → ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = (((𝑁 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) | 
| 81 | 78, 80 | eqeq12d 2752 | . . . . . . 7
⊢ (𝑥 = (𝑁 + 1) → ((♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) ↔ (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))}) = (((𝑁 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) | 
| 82 | 74, 81 | imbi12d 344 | . . . . . 6
⊢ (𝑥 = (𝑁 + 1) → ((𝑥 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) ↔ ((𝑁 + 1) ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))}) = (((𝑁 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))))) | 
| 83 | 82 | imbi2d 340 | . . . . 5
⊢ (𝑥 = (𝑁 + 1) → ((𝑁 ∈ ℕ → (𝑥 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑥)}) = ((𝑥 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) ↔ (𝑁 ∈ ℕ → ((𝑁 + 1) ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))}) = (((𝑁 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))))) | 
| 84 |  | hash0 14407 | . . . . . . 7
⊢
(♯‘∅) = 0 | 
| 85 |  | fveq2 6905 | . . . . . . . . . . . . . . . 16
⊢ (𝑦 = 1 → (𝑓‘𝑦) = (𝑓‘1)) | 
| 86 |  | id 22 | . . . . . . . . . . . . . . . 16
⊢ (𝑦 = 1 → 𝑦 = 1) | 
| 87 | 85, 86 | neeq12d 3001 | . . . . . . . . . . . . . . 15
⊢ (𝑦 = 1 → ((𝑓‘𝑦) ≠ 𝑦 ↔ (𝑓‘1) ≠ 1)) | 
| 88 | 87 | rspcv 3617 | . . . . . . . . . . . . . 14
⊢ (1 ∈
(1...(𝑁 + 1)) →
(∀𝑦 ∈
(1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦 → (𝑓‘1) ≠ 1)) | 
| 89 | 16, 88 | syl 17 | . . . . . . . . . . . . 13
⊢ (𝑁 ∈ ℕ →
(∀𝑦 ∈
(1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦 → (𝑓‘1) ≠ 1)) | 
| 90 | 89 | adantld 490 | . . . . . . . . . . . 12
⊢ (𝑁 ∈ ℕ → ((𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦) → (𝑓‘1) ≠ 1)) | 
| 91 | 90 | ss2abdv 4065 | . . . . . . . . . . 11
⊢ (𝑁 ∈ ℕ → {𝑓 ∣ (𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)} ⊆ {𝑓 ∣ (𝑓‘1) ≠ 1}) | 
| 92 |  | df-ne 2940 | . . . . . . . . . . . . 13
⊢ ((𝑔‘1) ≠ 1 ↔ ¬
(𝑔‘1) =
1) | 
| 93 | 23 | neeq1d 2999 | . . . . . . . . . . . . 13
⊢ (𝑔 = 𝑓 → ((𝑔‘1) ≠ 1 ↔ (𝑓‘1) ≠ 1)) | 
| 94 | 92, 93 | bitr3id 285 | . . . . . . . . . . . 12
⊢ (𝑔 = 𝑓 → (¬ (𝑔‘1) = 1 ↔ (𝑓‘1) ≠ 1)) | 
| 95 | 94 | cbvabv 2811 | . . . . . . . . . . 11
⊢ {𝑔 ∣ ¬ (𝑔‘1) = 1} = {𝑓 ∣ (𝑓‘1) ≠ 1} | 
| 96 | 91, 10, 95 | 3sstr4g 4036 | . . . . . . . . . 10
⊢ (𝑁 ∈ ℕ → 𝐴 ⊆ {𝑔 ∣ ¬ (𝑔‘1) = 1}) | 
| 97 |  | ssabral 4064 | . . . . . . . . . 10
⊢ (𝐴 ⊆ {𝑔 ∣ ¬ (𝑔‘1) = 1} ↔ ∀𝑔 ∈ 𝐴 ¬ (𝑔‘1) = 1) | 
| 98 | 96, 97 | sylib 218 | . . . . . . . . 9
⊢ (𝑁 ∈ ℕ →
∀𝑔 ∈ 𝐴 ¬ (𝑔‘1) = 1) | 
| 99 |  | rabeq0 4387 | . . . . . . . . 9
⊢ ({𝑔 ∈ 𝐴 ∣ (𝑔‘1) = 1} = ∅ ↔ ∀𝑔 ∈ 𝐴 ¬ (𝑔‘1) = 1) | 
| 100 | 98, 99 | sylibr 234 | . . . . . . . 8
⊢ (𝑁 ∈ ℕ → {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = 1} = ∅) | 
| 101 | 100 | fveq2d 6909 | . . . . . . 7
⊢ (𝑁 ∈ ℕ →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) = 1}) =
(♯‘∅)) | 
| 102 |  | nnnn0 12535 | . . . . . . . . . . 11
⊢ (𝑁 ∈ ℕ → 𝑁 ∈
ℕ0) | 
| 103 | 3, 4 | subfacf 35181 | . . . . . . . . . . . 12
⊢ 𝑆:ℕ0⟶ℕ0 | 
| 104 | 103 | ffvelcdmi 7102 | . . . . . . . . . . 11
⊢ (𝑁 ∈ ℕ0
→ (𝑆‘𝑁) ∈
ℕ0) | 
| 105 | 102, 104 | syl 17 | . . . . . . . . . 10
⊢ (𝑁 ∈ ℕ → (𝑆‘𝑁) ∈
ℕ0) | 
| 106 |  | nnm1nn0 12569 | . . . . . . . . . . 11
⊢ (𝑁 ∈ ℕ → (𝑁 − 1) ∈
ℕ0) | 
| 107 | 103 | ffvelcdmi 7102 | . . . . . . . . . . 11
⊢ ((𝑁 − 1) ∈
ℕ0 → (𝑆‘(𝑁 − 1)) ∈
ℕ0) | 
| 108 | 106, 107 | syl 17 | . . . . . . . . . 10
⊢ (𝑁 ∈ ℕ → (𝑆‘(𝑁 − 1)) ∈
ℕ0) | 
| 109 | 105, 108 | nn0addcld 12593 | . . . . . . . . 9
⊢ (𝑁 ∈ ℕ → ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))) ∈
ℕ0) | 
| 110 | 109 | nn0cnd 12591 | . . . . . . . 8
⊢ (𝑁 ∈ ℕ → ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))) ∈
ℂ) | 
| 111 | 110 | mul02d 11460 | . . . . . . 7
⊢ (𝑁 ∈ ℕ → (0
· ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = 0) | 
| 112 | 84, 101, 111 | 3eqtr4a 2802 | . . . . . 6
⊢ (𝑁 ∈ ℕ →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) = 1}) = (0 ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) | 
| 113 | 112 | a1d 25 | . . . . 5
⊢ (𝑁 ∈ ℕ → (1 ∈
(1...(𝑁 + 1)) →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) = 1}) = (0 ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) | 
| 114 |  | simplr 768 | . . . . . . . . . . . 12
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → 𝑚 ∈
ℕ) | 
| 115 | 114, 13 | eleqtrdi 2850 | . . . . . . . . . . 11
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → 𝑚 ∈
(ℤ≥‘1)) | 
| 116 |  | peano2fzr 13578 | . . . . . . . . . . 11
⊢ ((𝑚 ∈
(ℤ≥‘1) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → 𝑚 ∈ (1...(𝑁 + 1))) | 
| 117 | 115, 116 | sylancom 588 | . . . . . . . . . 10
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → 𝑚 ∈ (1...(𝑁 + 1))) | 
| 118 | 117 | ex 412 | . . . . . . . . 9
⊢ ((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) → 𝑚 ∈ (1...(𝑁 + 1)))) | 
| 119 | 118 | imim1d 82 | . . . . . . . 8
⊢ ((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) → ((𝑚 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))))) | 
| 120 |  | oveq1 7439 | . . . . . . . . . . 11
⊢
((♯‘{𝑔
∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) → ((♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) + (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)})) = (((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) + (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}))) | 
| 121 |  | elfzp1 13615 | . . . . . . . . . . . . . . . . 17
⊢ (𝑚 ∈
(ℤ≥‘1) → ((𝑔‘1) ∈ (1...(𝑚 + 1)) ↔ ((𝑔‘1) ∈ (1...𝑚) ∨ (𝑔‘1) = (𝑚 + 1)))) | 
| 122 | 115, 121 | syl 17 | . . . . . . . . . . . . . . . 16
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → ((𝑔‘1) ∈ (1...(𝑚 + 1)) ↔ ((𝑔‘1) ∈ (1...𝑚) ∨ (𝑔‘1) = (𝑚 + 1)))) | 
| 123 | 122 | rabbidv 3443 | . . . . . . . . . . . . . . 15
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))} = {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) ∈ (1...𝑚) ∨ (𝑔‘1) = (𝑚 + 1))}) | 
| 124 |  | unrab 4314 | . . . . . . . . . . . . . . 15
⊢ ({𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∪ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}) = {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) ∈ (1...𝑚) ∨ (𝑔‘1) = (𝑚 + 1))} | 
| 125 | 123, 124 | eqtr4di 2794 | . . . . . . . . . . . . . 14
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))} = ({𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∪ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)})) | 
| 126 | 125 | fveq2d 6909 | . . . . . . . . . . . . 13
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) =
(♯‘({𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∪ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}))) | 
| 127 |  | fzfi 14014 | . . . . . . . . . . . . . . . . 17
⊢
(1...(𝑁 + 1)) ∈
Fin | 
| 128 |  | deranglem 35172 | . . . . . . . . . . . . . . . . 17
⊢
((1...(𝑁 + 1))
∈ Fin → {𝑓
∣ (𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)} ∈ Fin) | 
| 129 | 127, 128 | ax-mp 5 | . . . . . . . . . . . . . . . 16
⊢ {𝑓 ∣ (𝑓:(1...(𝑁 + 1))–1-1-onto→(1...(𝑁 + 1)) ∧ ∀𝑦 ∈ (1...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)} ∈ Fin | 
| 130 | 10, 129 | eqeltri 2836 | . . . . . . . . . . . . . . 15
⊢ 𝐴 ∈ Fin | 
| 131 |  | ssrab2 4079 | . . . . . . . . . . . . . . 15
⊢ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ⊆ 𝐴 | 
| 132 |  | ssfi 9214 | . . . . . . . . . . . . . . 15
⊢ ((𝐴 ∈ Fin ∧ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ⊆ 𝐴) → {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∈ Fin) | 
| 133 | 130, 131,
132 | mp2an 692 | . . . . . . . . . . . . . 14
⊢ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∈ Fin | 
| 134 |  | ssrab2 4079 | . . . . . . . . . . . . . . 15
⊢ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)} ⊆ 𝐴 | 
| 135 |  | ssfi 9214 | . . . . . . . . . . . . . . 15
⊢ ((𝐴 ∈ Fin ∧ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)} ⊆ 𝐴) → {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)} ∈ Fin) | 
| 136 | 130, 134,
135 | mp2an 692 | . . . . . . . . . . . . . 14
⊢ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)} ∈ Fin | 
| 137 |  | inrab 4315 | . . . . . . . . . . . . . . 15
⊢ ({𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∩ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}) = {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) ∈ (1...𝑚) ∧ (𝑔‘1) = (𝑚 + 1))} | 
| 138 |  | fzp1disj 13624 | . . . . . . . . . . . . . . . . . 18
⊢
((1...𝑚) ∩
{(𝑚 + 1)}) =
∅ | 
| 139 | 42 | elsn 4640 | . . . . . . . . . . . . . . . . . . . 20
⊢ ((𝑔‘1) ∈ {(𝑚 + 1)} ↔ (𝑔‘1) = (𝑚 + 1)) | 
| 140 |  | inelcm 4464 | . . . . . . . . . . . . . . . . . . . 20
⊢ (((𝑔‘1) ∈ (1...𝑚) ∧ (𝑔‘1) ∈ {(𝑚 + 1)}) → ((1...𝑚) ∩ {(𝑚 + 1)}) ≠ ∅) | 
| 141 | 139, 140 | sylan2br 595 | . . . . . . . . . . . . . . . . . . 19
⊢ (((𝑔‘1) ∈ (1...𝑚) ∧ (𝑔‘1) = (𝑚 + 1)) → ((1...𝑚) ∩ {(𝑚 + 1)}) ≠ ∅) | 
| 142 | 141 | necon2bi 2970 | . . . . . . . . . . . . . . . . . 18
⊢
(((1...𝑚) ∩
{(𝑚 + 1)}) = ∅ →
¬ ((𝑔‘1) ∈
(1...𝑚) ∧ (𝑔‘1) = (𝑚 + 1))) | 
| 143 | 138, 142 | ax-mp 5 | . . . . . . . . . . . . . . . . 17
⊢  ¬
((𝑔‘1) ∈
(1...𝑚) ∧ (𝑔‘1) = (𝑚 + 1)) | 
| 144 | 143 | rgenw 3064 | . . . . . . . . . . . . . . . 16
⊢
∀𝑔 ∈
𝐴 ¬ ((𝑔‘1) ∈ (1...𝑚) ∧ (𝑔‘1) = (𝑚 + 1)) | 
| 145 |  | rabeq0 4387 | . . . . . . . . . . . . . . . 16
⊢ ({𝑔 ∈ 𝐴 ∣ ((𝑔‘1) ∈ (1...𝑚) ∧ (𝑔‘1) = (𝑚 + 1))} = ∅ ↔ ∀𝑔 ∈ 𝐴 ¬ ((𝑔‘1) ∈ (1...𝑚) ∧ (𝑔‘1) = (𝑚 + 1))) | 
| 146 | 144, 145 | mpbir 231 | . . . . . . . . . . . . . . 15
⊢ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) ∈ (1...𝑚) ∧ (𝑔‘1) = (𝑚 + 1))} = ∅ | 
| 147 | 137, 146 | eqtri 2764 | . . . . . . . . . . . . . 14
⊢ ({𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∩ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}) = ∅ | 
| 148 |  | hashun 14422 | . . . . . . . . . . . . . 14
⊢ (({𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∈ Fin ∧ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)} ∈ Fin ∧ ({𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∩ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}) = ∅) →
(♯‘({𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∪ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)})) = ((♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) + (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}))) | 
| 149 | 133, 136,
147, 148 | mp3an 1462 | . . . . . . . . . . . . 13
⊢
(♯‘({𝑔
∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)} ∪ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)})) = ((♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) + (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)})) | 
| 150 | 126, 149 | eqtrdi 2792 | . . . . . . . . . . . 12
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) =
((♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) + (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}))) | 
| 151 |  | nncn 12275 | . . . . . . . . . . . . . . . 16
⊢ (𝑚 ∈ ℕ → 𝑚 ∈
ℂ) | 
| 152 | 151 | ad2antlr 727 | . . . . . . . . . . . . . . 15
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → 𝑚 ∈
ℂ) | 
| 153 |  | ax-1cn 11214 | . . . . . . . . . . . . . . . 16
⊢ 1 ∈
ℂ | 
| 154 | 153 | a1i 11 | . . . . . . . . . . . . . . 15
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → 1 ∈
ℂ) | 
| 155 | 152, 154,
154 | addsubd 11642 | . . . . . . . . . . . . . 14
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → ((𝑚 + 1) − 1) = ((𝑚 − 1) +
1)) | 
| 156 | 155 | oveq1d 7447 | . . . . . . . . . . . . 13
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (((𝑚 + 1) − 1) ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = (((𝑚 − 1) + 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) | 
| 157 |  | subcl 11508 | . . . . . . . . . . . . . . 15
⊢ ((𝑚 ∈ ℂ ∧ 1 ∈
ℂ) → (𝑚 −
1) ∈ ℂ) | 
| 158 | 152, 153,
157 | sylancl 586 | . . . . . . . . . . . . . 14
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (𝑚 − 1) ∈
ℂ) | 
| 159 | 109 | ad2antrr 726 | . . . . . . . . . . . . . . 15
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))) ∈
ℕ0) | 
| 160 | 159 | nn0cnd 12591 | . . . . . . . . . . . . . 14
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))) ∈
ℂ) | 
| 161 | 158, 154,
160 | adddird 11287 | . . . . . . . . . . . . 13
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (((𝑚 − 1) + 1) ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = (((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) + (1 · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) | 
| 162 | 160 | mullidd 11280 | . . . . . . . . . . . . . . 15
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (1 ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) | 
| 163 |  | exmidne 2949 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ ((𝑔‘(𝑚 + 1)) = 1 ∨ (𝑔‘(𝑚 + 1)) ≠ 1) | 
| 164 |  | orcom 870 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ (((𝑔‘(𝑚 + 1)) = 1 ∨ (𝑔‘(𝑚 + 1)) ≠ 1) ↔ ((𝑔‘(𝑚 + 1)) ≠ 1 ∨ (𝑔‘(𝑚 + 1)) = 1)) | 
| 165 | 163, 164 | mpbi 230 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ ((𝑔‘(𝑚 + 1)) ≠ 1 ∨ (𝑔‘(𝑚 + 1)) = 1) | 
| 166 | 165 | biantru 529 | . . . . . . . . . . . . . . . . . . . . 21
⊢ ((𝑔‘1) = (𝑚 + 1) ↔ ((𝑔‘1) = (𝑚 + 1) ∧ ((𝑔‘(𝑚 + 1)) ≠ 1 ∨ (𝑔‘(𝑚 + 1)) = 1))) | 
| 167 |  | andi 1009 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (((𝑔‘1) = (𝑚 + 1) ∧ ((𝑔‘(𝑚 + 1)) ≠ 1 ∨ (𝑔‘(𝑚 + 1)) = 1)) ↔ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∨ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1))) | 
| 168 | 166, 167 | bitri 275 | . . . . . . . . . . . . . . . . . . . 20
⊢ ((𝑔‘1) = (𝑚 + 1) ↔ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∨ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1))) | 
| 169 | 168 | rabbii 3441 | . . . . . . . . . . . . . . . . . . 19
⊢ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)} = {𝑔 ∈ 𝐴 ∣ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∨ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1))} | 
| 170 |  | unrab 4314 | . . . . . . . . . . . . . . . . . . 19
⊢ ({𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∪ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)}) = {𝑔 ∈ 𝐴 ∣ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∨ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1))} | 
| 171 | 169, 170 | eqtr4i 2767 | . . . . . . . . . . . . . . . . . 18
⊢ {𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)} = ({𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∪ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)}) | 
| 172 | 171 | fveq2i 6908 | . . . . . . . . . . . . . . . . 17
⊢
(♯‘{𝑔
∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}) = (♯‘({𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∪ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)})) | 
| 173 |  | ssrab2 4079 | . . . . . . . . . . . . . . . . . . 19
⊢ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ⊆ 𝐴 | 
| 174 |  | ssfi 9214 | . . . . . . . . . . . . . . . . . . 19
⊢ ((𝐴 ∈ Fin ∧ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ⊆ 𝐴) → {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∈ Fin) | 
| 175 | 130, 173,
174 | mp2an 692 | . . . . . . . . . . . . . . . . . 18
⊢ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∈ Fin | 
| 176 |  | ssrab2 4079 | . . . . . . . . . . . . . . . . . . 19
⊢ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)} ⊆ 𝐴 | 
| 177 |  | ssfi 9214 | . . . . . . . . . . . . . . . . . . 19
⊢ ((𝐴 ∈ Fin ∧ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)} ⊆ 𝐴) → {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)} ∈ Fin) | 
| 178 | 130, 176,
177 | mp2an 692 | . . . . . . . . . . . . . . . . . 18
⊢ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)} ∈ Fin | 
| 179 |  | inrab 4315 | . . . . . . . . . . . . . . . . . . 19
⊢ ({𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∩ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)}) = {𝑔 ∈ 𝐴 ∣ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∧ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1))} | 
| 180 |  | simpr 484 | . . . . . . . . . . . . . . . . . . . . . . . 24
⊢ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1) → (𝑔‘(𝑚 + 1)) = 1) | 
| 181 | 180 | necon3ai 2964 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ ((𝑔‘(𝑚 + 1)) ≠ 1 → ¬ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)) | 
| 182 | 181 | adantl 481 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) → ¬ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)) | 
| 183 |  | imnan 399 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ ((((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) → ¬ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)) ↔ ¬ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∧ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1))) | 
| 184 | 182, 183 | mpbi 230 | . . . . . . . . . . . . . . . . . . . . 21
⊢  ¬
(((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∧ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)) | 
| 185 | 184 | rgenw 3064 | . . . . . . . . . . . . . . . . . . . 20
⊢
∀𝑔 ∈
𝐴 ¬ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∧ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)) | 
| 186 |  | rabeq0 4387 | . . . . . . . . . . . . . . . . . . . 20
⊢ ({𝑔 ∈ 𝐴 ∣ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∧ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1))} = ∅ ↔ ∀𝑔 ∈ 𝐴 ¬ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∧ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1))) | 
| 187 | 185, 186 | mpbir 231 | . . . . . . . . . . . . . . . . . . 19
⊢ {𝑔 ∈ 𝐴 ∣ (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ∧ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1))} = ∅ | 
| 188 | 179, 187 | eqtri 2764 | . . . . . . . . . . . . . . . . . 18
⊢ ({𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∩ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)}) = ∅ | 
| 189 |  | hashun 14422 | . . . . . . . . . . . . . . . . . 18
⊢ (({𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∈ Fin ∧ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)} ∈ Fin ∧ ({𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∩ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)}) = ∅) →
(♯‘({𝑔 ∈
𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∪ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)})) = ((♯‘{𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)}) + (♯‘{𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)}))) | 
| 190 | 175, 178,
188, 189 | mp3an 1462 | . . . . . . . . . . . . . . . . 17
⊢
(♯‘({𝑔
∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} ∪ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)})) = ((♯‘{𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)}) + (♯‘{𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)})) | 
| 191 | 172, 190 | eqtri 2764 | . . . . . . . . . . . . . . . 16
⊢
(♯‘{𝑔
∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}) = ((♯‘{𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)}) + (♯‘{𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)})) | 
| 192 |  | simpll 766 | . . . . . . . . . . . . . . . . . 18
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → 𝑁 ∈ ℕ) | 
| 193 |  | nnne0 12301 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ (𝑚 ∈ ℕ → 𝑚 ≠ 0) | 
| 194 |  | 0p1e1 12389 | . . . . . . . . . . . . . . . . . . . . . . . . 25
⊢ (0 + 1) =
1 | 
| 195 | 194 | eqeq2i 2749 | . . . . . . . . . . . . . . . . . . . . . . . 24
⊢ ((𝑚 + 1) = (0 + 1) ↔ (𝑚 + 1) = 1) | 
| 196 |  | 0cn 11254 | . . . . . . . . . . . . . . . . . . . . . . . . . 26
⊢ 0 ∈
ℂ | 
| 197 |  | addcan2 11447 | . . . . . . . . . . . . . . . . . . . . . . . . . 26
⊢ ((𝑚 ∈ ℂ ∧ 0 ∈
ℂ ∧ 1 ∈ ℂ) → ((𝑚 + 1) = (0 + 1) ↔ 𝑚 = 0)) | 
| 198 | 196, 153,
197 | mp3an23 1454 | . . . . . . . . . . . . . . . . . . . . . . . . 25
⊢ (𝑚 ∈ ℂ → ((𝑚 + 1) = (0 + 1) ↔ 𝑚 = 0)) | 
| 199 | 151, 198 | syl 17 | . . . . . . . . . . . . . . . . . . . . . . . 24
⊢ (𝑚 ∈ ℕ → ((𝑚 + 1) = (0 + 1) ↔ 𝑚 = 0)) | 
| 200 | 195, 199 | bitr3id 285 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ (𝑚 ∈ ℕ → ((𝑚 + 1) = 1 ↔ 𝑚 = 0)) | 
| 201 | 200 | necon3bbid 2977 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ (𝑚 ∈ ℕ → (¬
(𝑚 + 1) = 1 ↔ 𝑚 ≠ 0)) | 
| 202 | 193, 201 | mpbird 257 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (𝑚 ∈ ℕ → ¬
(𝑚 + 1) =
1) | 
| 203 | 202 | ad2antlr 727 | . . . . . . . . . . . . . . . . . . . 20
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → ¬ (𝑚 + 1) = 1) | 
| 204 | 14 | adantr 480 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ ((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) → (𝑁 + 1) ∈
(ℤ≥‘1)) | 
| 205 |  | elfzp12 13644 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ ((𝑁 + 1) ∈
(ℤ≥‘1) → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) ↔ ((𝑚 + 1) = 1 ∨ (𝑚 + 1) ∈ ((1 + 1)...(𝑁 + 1))))) | 
| 206 | 204, 205 | syl 17 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ ((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) ↔ ((𝑚 + 1) = 1 ∨ (𝑚 + 1) ∈ ((1 + 1)...(𝑁 + 1))))) | 
| 207 | 206 | biimpa 476 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → ((𝑚 + 1) = 1 ∨ (𝑚 + 1) ∈ ((1 + 1)...(𝑁 + 1)))) | 
| 208 | 207 | ord 864 | . . . . . . . . . . . . . . . . . . . 20
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (¬ (𝑚 + 1) = 1 → (𝑚 + 1) ∈ ((1 + 1)...(𝑁 + 1)))) | 
| 209 | 203, 208 | mpd 15 | . . . . . . . . . . . . . . . . . . 19
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (𝑚 + 1) ∈ ((1 + 1)...(𝑁 + 1))) | 
| 210 |  | df-2 12330 | . . . . . . . . . . . . . . . . . . . 20
⊢ 2 = (1 +
1) | 
| 211 | 210 | oveq1i 7442 | . . . . . . . . . . . . . . . . . . 19
⊢
(2...(𝑁 + 1)) = ((1
+ 1)...(𝑁 +
1)) | 
| 212 | 209, 211 | eleqtrrdi 2851 | . . . . . . . . . . . . . . . . . 18
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (𝑚 + 1) ∈ (2...(𝑁 + 1))) | 
| 213 |  | ovex 7465 | . . . . . . . . . . . . . . . . . 18
⊢ (𝑚 + 1) ∈ V | 
| 214 |  | eqid 2736 | . . . . . . . . . . . . . . . . . 18
⊢
((2...(𝑁 + 1))
∖ {(𝑚 + 1)}) =
((2...(𝑁 + 1)) ∖
{(𝑚 + 1)}) | 
| 215 |  | fveq1 6904 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (𝑔 = ℎ → (𝑔‘1) = (ℎ‘1)) | 
| 216 | 215 | eqeq1d 2738 | . . . . . . . . . . . . . . . . . . . 20
⊢ (𝑔 = ℎ → ((𝑔‘1) = (𝑚 + 1) ↔ (ℎ‘1) = (𝑚 + 1))) | 
| 217 |  | fveq1 6904 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (𝑔 = ℎ → (𝑔‘(𝑚 + 1)) = (ℎ‘(𝑚 + 1))) | 
| 218 | 217 | neeq1d 2999 | . . . . . . . . . . . . . . . . . . . 20
⊢ (𝑔 = ℎ → ((𝑔‘(𝑚 + 1)) ≠ 1 ↔ (ℎ‘(𝑚 + 1)) ≠ 1)) | 
| 219 | 216, 218 | anbi12d 632 | . . . . . . . . . . . . . . . . . . 19
⊢ (𝑔 = ℎ → (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1) ↔ ((ℎ‘1) = (𝑚 + 1) ∧ (ℎ‘(𝑚 + 1)) ≠ 1))) | 
| 220 | 219 | cbvrabv 3446 | . . . . . . . . . . . . . . . . . 18
⊢ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)} = {ℎ ∈ 𝐴 ∣ ((ℎ‘1) = (𝑚 + 1) ∧ (ℎ‘(𝑚 + 1)) ≠ 1)} | 
| 221 |  | eqid 2736 | . . . . . . . . . . . . . . . . . 18
⊢ (( I
↾ ((2...(𝑁 + 1))
∖ {(𝑚 + 1)})) ∪
{〈1, (𝑚 + 1)〉,
〈(𝑚 + 1), 1〉}) =
(( I ↾ ((2...(𝑁 + 1))
∖ {(𝑚 + 1)})) ∪
{〈1, (𝑚 + 1)〉,
〈(𝑚 + 1),
1〉}) | 
| 222 |  | f1oeq1 6835 | . . . . . . . . . . . . . . . . . . . 20
⊢ (𝑔 = 𝑓 → (𝑔:(2...(𝑁 + 1))–1-1-onto→(2...(𝑁 + 1)) ↔ 𝑓:(2...(𝑁 + 1))–1-1-onto→(2...(𝑁 + 1)))) | 
| 223 |  | fveq2 6905 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ (𝑧 = 𝑦 → (𝑔‘𝑧) = (𝑔‘𝑦)) | 
| 224 |  | id 22 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ (𝑧 = 𝑦 → 𝑧 = 𝑦) | 
| 225 | 223, 224 | neeq12d 3001 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ (𝑧 = 𝑦 → ((𝑔‘𝑧) ≠ 𝑧 ↔ (𝑔‘𝑦) ≠ 𝑦)) | 
| 226 | 225 | cbvralvw 3236 | . . . . . . . . . . . . . . . . . . . . 21
⊢
(∀𝑧 ∈
(2...(𝑁 + 1))(𝑔‘𝑧) ≠ 𝑧 ↔ ∀𝑦 ∈ (2...(𝑁 + 1))(𝑔‘𝑦) ≠ 𝑦) | 
| 227 |  | fveq1 6904 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ (𝑔 = 𝑓 → (𝑔‘𝑦) = (𝑓‘𝑦)) | 
| 228 | 227 | neeq1d 2999 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ (𝑔 = 𝑓 → ((𝑔‘𝑦) ≠ 𝑦 ↔ (𝑓‘𝑦) ≠ 𝑦)) | 
| 229 | 228 | ralbidv 3177 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (𝑔 = 𝑓 → (∀𝑦 ∈ (2...(𝑁 + 1))(𝑔‘𝑦) ≠ 𝑦 ↔ ∀𝑦 ∈ (2...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)) | 
| 230 | 226, 229 | bitrid 283 | . . . . . . . . . . . . . . . . . . . 20
⊢ (𝑔 = 𝑓 → (∀𝑧 ∈ (2...(𝑁 + 1))(𝑔‘𝑧) ≠ 𝑧 ↔ ∀𝑦 ∈ (2...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)) | 
| 231 | 222, 230 | anbi12d 632 | . . . . . . . . . . . . . . . . . . 19
⊢ (𝑔 = 𝑓 → ((𝑔:(2...(𝑁 + 1))–1-1-onto→(2...(𝑁 + 1)) ∧ ∀𝑧 ∈ (2...(𝑁 + 1))(𝑔‘𝑧) ≠ 𝑧) ↔ (𝑓:(2...(𝑁 + 1))–1-1-onto→(2...(𝑁 + 1)) ∧ ∀𝑦 ∈ (2...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦))) | 
| 232 | 231 | cbvabv 2811 | . . . . . . . . . . . . . . . . . 18
⊢ {𝑔 ∣ (𝑔:(2...(𝑁 + 1))–1-1-onto→(2...(𝑁 + 1)) ∧ ∀𝑧 ∈ (2...(𝑁 + 1))(𝑔‘𝑧) ≠ 𝑧)} = {𝑓 ∣ (𝑓:(2...(𝑁 + 1))–1-1-onto→(2...(𝑁 + 1)) ∧ ∀𝑦 ∈ (2...(𝑁 + 1))(𝑓‘𝑦) ≠ 𝑦)} | 
| 233 | 3, 4, 10, 192, 212, 213, 214, 220, 221, 232 | subfacp1lem5 35190 | . . . . . . . . . . . . . . . . 17
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) →
(♯‘{𝑔 ∈
𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)}) = (𝑆‘𝑁)) | 
| 234 | 217 | eqeq1d 2738 | . . . . . . . . . . . . . . . . . . . 20
⊢ (𝑔 = ℎ → ((𝑔‘(𝑚 + 1)) = 1 ↔ (ℎ‘(𝑚 + 1)) = 1)) | 
| 235 | 216, 234 | anbi12d 632 | . . . . . . . . . . . . . . . . . . 19
⊢ (𝑔 = ℎ → (((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1) ↔ ((ℎ‘1) = (𝑚 + 1) ∧ (ℎ‘(𝑚 + 1)) = 1))) | 
| 236 | 235 | cbvrabv 3446 | . . . . . . . . . . . . . . . . . 18
⊢ {𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)} = {ℎ ∈ 𝐴 ∣ ((ℎ‘1) = (𝑚 + 1) ∧ (ℎ‘(𝑚 + 1)) = 1)} | 
| 237 |  | f1oeq1 6835 | . . . . . . . . . . . . . . . . . . . 20
⊢ (𝑔 = 𝑓 → (𝑔:((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})–1-1-onto→((2...(𝑁 + 1)) ∖ {(𝑚 + 1)}) ↔ 𝑓:((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})–1-1-onto→((2...(𝑁 + 1)) ∖ {(𝑚 + 1)}))) | 
| 238 | 225 | cbvralvw 3236 | . . . . . . . . . . . . . . . . . . . . 21
⊢
(∀𝑧 ∈
((2...(𝑁 + 1)) ∖
{(𝑚 + 1)})(𝑔‘𝑧) ≠ 𝑧 ↔ ∀𝑦 ∈ ((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})(𝑔‘𝑦) ≠ 𝑦) | 
| 239 | 228 | ralbidv 3177 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (𝑔 = 𝑓 → (∀𝑦 ∈ ((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})(𝑔‘𝑦) ≠ 𝑦 ↔ ∀𝑦 ∈ ((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})(𝑓‘𝑦) ≠ 𝑦)) | 
| 240 | 238, 239 | bitrid 283 | . . . . . . . . . . . . . . . . . . . 20
⊢ (𝑔 = 𝑓 → (∀𝑧 ∈ ((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})(𝑔‘𝑧) ≠ 𝑧 ↔ ∀𝑦 ∈ ((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})(𝑓‘𝑦) ≠ 𝑦)) | 
| 241 | 237, 240 | anbi12d 632 | . . . . . . . . . . . . . . . . . . 19
⊢ (𝑔 = 𝑓 → ((𝑔:((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})–1-1-onto→((2...(𝑁 + 1)) ∖ {(𝑚 + 1)}) ∧ ∀𝑧 ∈ ((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})(𝑔‘𝑧) ≠ 𝑧) ↔ (𝑓:((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})–1-1-onto→((2...(𝑁 + 1)) ∖ {(𝑚 + 1)}) ∧ ∀𝑦 ∈ ((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})(𝑓‘𝑦) ≠ 𝑦))) | 
| 242 | 241 | cbvabv 2811 | . . . . . . . . . . . . . . . . . 18
⊢ {𝑔 ∣ (𝑔:((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})–1-1-onto→((2...(𝑁 + 1)) ∖ {(𝑚 + 1)}) ∧ ∀𝑧 ∈ ((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})(𝑔‘𝑧) ≠ 𝑧)} = {𝑓 ∣ (𝑓:((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})–1-1-onto→((2...(𝑁 + 1)) ∖ {(𝑚 + 1)}) ∧ ∀𝑦 ∈ ((2...(𝑁 + 1)) ∖ {(𝑚 + 1)})(𝑓‘𝑦) ≠ 𝑦)} | 
| 243 | 3, 4, 10, 192, 212, 213, 214, 236, 242 | subfacp1lem3 35188 | . . . . . . . . . . . . . . . . 17
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) →
(♯‘{𝑔 ∈
𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)}) = (𝑆‘(𝑁 − 1))) | 
| 244 | 233, 243 | oveq12d 7450 | . . . . . . . . . . . . . . . 16
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) →
((♯‘{𝑔 ∈
𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) ≠ 1)}) + (♯‘{𝑔 ∈ 𝐴 ∣ ((𝑔‘1) = (𝑚 + 1) ∧ (𝑔‘(𝑚 + 1)) = 1)})) = ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) | 
| 245 | 191, 244 | eqtrid 2788 | . . . . . . . . . . . . . . 15
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}) = ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) | 
| 246 | 162, 245 | eqtr4d 2779 | . . . . . . . . . . . . . 14
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (1 ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)})) | 
| 247 | 246 | oveq2d 7448 | . . . . . . . . . . . . 13
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) + (1 · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) = (((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) + (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}))) | 
| 248 | 156, 161,
247 | 3eqtrd 2780 | . . . . . . . . . . . 12
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) → (((𝑚 + 1) − 1) ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = (((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) + (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)}))) | 
| 249 | 150, 248 | eqeq12d 2752 | . . . . . . . . . . 11
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) →
((♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) ↔ ((♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) + (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)})) = (((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) + (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) = (𝑚 + 1)})))) | 
| 250 | 120, 249 | imbitrrid 246 | . . . . . . . . . 10
⊢ (((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) ∧ (𝑚 + 1) ∈ (1...(𝑁 + 1))) →
((♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) | 
| 251 | 250 | ex 412 | . . . . . . . . 9
⊢ ((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) →
((♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))))) | 
| 252 | 251 | a2d 29 | . . . . . . . 8
⊢ ((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) → (((𝑚 + 1) ∈ (1...(𝑁 + 1)) →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))))) | 
| 253 | 119, 252 | syld 47 | . . . . . . 7
⊢ ((𝑁 ∈ ℕ ∧ 𝑚 ∈ ℕ) → ((𝑚 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))))) | 
| 254 | 253 | expcom 413 | . . . . . 6
⊢ (𝑚 ∈ ℕ → (𝑁 ∈ ℕ → ((𝑚 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))))) | 
| 255 | 254 | a2d 29 | . . . . 5
⊢ (𝑚 ∈ ℕ → ((𝑁 ∈ ℕ → (𝑚 ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...𝑚)}) = ((𝑚 − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) → (𝑁 ∈ ℕ → ((𝑚 + 1) ∈ (1...(𝑁 + 1)) → (♯‘{𝑔 ∈ 𝐴 ∣ (𝑔‘1) ∈ (1...(𝑚 + 1))}) = (((𝑚 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))))) | 
| 256 | 53, 63, 73, 83, 113, 255 | nnind 12285 | . . . 4
⊢ ((𝑁 + 1) ∈ ℕ →
(𝑁 ∈ ℕ →
((𝑁 + 1) ∈ (1...(𝑁 + 1)) →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))}) = (((𝑁 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))))) | 
| 257 | 1, 256 | mpcom 38 | . . 3
⊢ (𝑁 ∈ ℕ → ((𝑁 + 1) ∈ (1...(𝑁 + 1)) →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))}) = (((𝑁 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))))) | 
| 258 | 34, 257 | mpd 15 | . 2
⊢ (𝑁 ∈ ℕ →
(♯‘{𝑔 ∈
𝐴 ∣ (𝑔‘1) ∈ (1...(𝑁 + 1))}) = (((𝑁 + 1) − 1) · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) | 
| 259 |  | nncn 12275 | . . . 4
⊢ (𝑁 ∈ ℕ → 𝑁 ∈
ℂ) | 
| 260 |  | pncan 11515 | . . . 4
⊢ ((𝑁 ∈ ℂ ∧ 1 ∈
ℂ) → ((𝑁 + 1)
− 1) = 𝑁) | 
| 261 | 259, 153,
260 | sylancl 586 | . . 3
⊢ (𝑁 ∈ ℕ → ((𝑁 + 1) − 1) = 𝑁) | 
| 262 | 261 | oveq1d 7447 | . 2
⊢ (𝑁 ∈ ℕ → (((𝑁 + 1) − 1) ·
((𝑆‘𝑁) + (𝑆‘(𝑁 − 1)))) = (𝑁 · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) | 
| 263 | 32, 258, 262 | 3eqtrd 2780 | 1
⊢ (𝑁 ∈ ℕ → (𝑆‘(𝑁 + 1)) = (𝑁 · ((𝑆‘𝑁) + (𝑆‘(𝑁 − 1))))) |