| Step | Hyp | Ref
 | Expression | 
| 1 |   | iseqid.3 | 
. 2
⊢ (𝜑 → 𝑁 ∈ (ℤ≥‘𝑀)) | 
| 2 |   | eluzelz 9610 | 
. . . . . 6
⊢ (𝑁 ∈
(ℤ≥‘𝑀) → 𝑁 ∈ ℤ) | 
| 3 | 1, 2 | syl 14 | 
. . . . 5
⊢ (𝜑 → 𝑁 ∈ ℤ) | 
| 4 |   | simpr 110 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝑥 ∈ (ℤ≥‘𝑁)) → 𝑥 ∈ (ℤ≥‘𝑁)) | 
| 5 | 1 | adantr 276 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝑥 ∈ (ℤ≥‘𝑁)) → 𝑁 ∈ (ℤ≥‘𝑀)) | 
| 6 |   | uztrn 9618 | 
. . . . . . 7
⊢ ((𝑥 ∈
(ℤ≥‘𝑁) ∧ 𝑁 ∈ (ℤ≥‘𝑀)) → 𝑥 ∈ (ℤ≥‘𝑀)) | 
| 7 | 4, 5, 6 | syl2anc 411 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑥 ∈ (ℤ≥‘𝑁)) → 𝑥 ∈ (ℤ≥‘𝑀)) | 
| 8 |   | iseqid.f | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑥 ∈ (ℤ≥‘𝑀)) → (𝐹‘𝑥) ∈ 𝑆) | 
| 9 | 7, 8 | syldan 282 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑥 ∈ (ℤ≥‘𝑁)) → (𝐹‘𝑥) ∈ 𝑆) | 
| 10 |   | iseqid.cl | 
. . . . 5
⊢ ((𝜑 ∧ (𝑥 ∈ 𝑆 ∧ 𝑦 ∈ 𝑆)) → (𝑥 + 𝑦) ∈ 𝑆) | 
| 11 | 3, 9, 10 | seq3-1 10554 | 
. . . 4
⊢ (𝜑 → (seq𝑁( + , 𝐹)‘𝑁) = (𝐹‘𝑁)) | 
| 12 |   | seqeq1 10542 | 
. . . . . 6
⊢ (𝑁 = 𝑀 → seq𝑁( + , 𝐹) = seq𝑀( + , 𝐹)) | 
| 13 | 12 | fveq1d 5560 | 
. . . . 5
⊢ (𝑁 = 𝑀 → (seq𝑁( + , 𝐹)‘𝑁) = (seq𝑀( + , 𝐹)‘𝑁)) | 
| 14 | 13 | eqeq1d 2205 | 
. . . 4
⊢ (𝑁 = 𝑀 → ((seq𝑁( + , 𝐹)‘𝑁) = (𝐹‘𝑁) ↔ (seq𝑀( + , 𝐹)‘𝑁) = (𝐹‘𝑁))) | 
| 15 | 11, 14 | syl5ibcom 155 | 
. . 3
⊢ (𝜑 → (𝑁 = 𝑀 → (seq𝑀( + , 𝐹)‘𝑁) = (𝐹‘𝑁))) | 
| 16 |   | eluzel2 9606 | 
. . . . . . . 8
⊢ (𝑁 ∈
(ℤ≥‘𝑀) → 𝑀 ∈ ℤ) | 
| 17 | 1, 16 | syl 14 | 
. . . . . . 7
⊢ (𝜑 → 𝑀 ∈ ℤ) | 
| 18 | 17 | adantr 276 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → 𝑀 ∈ ℤ) | 
| 19 |   | simpr 110 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) | 
| 20 | 8 | adantlr 477 | 
. . . . . 6
⊢ (((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) ∧ 𝑥 ∈ (ℤ≥‘𝑀)) → (𝐹‘𝑥) ∈ 𝑆) | 
| 21 | 10 | adantlr 477 | 
. . . . . 6
⊢ (((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) ∧ (𝑥 ∈ 𝑆 ∧ 𝑦 ∈ 𝑆)) → (𝑥 + 𝑦) ∈ 𝑆) | 
| 22 | 18, 19, 20, 21 | seq3m1 10565 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → (seq𝑀( + , 𝐹)‘𝑁) = ((seq𝑀( + , 𝐹)‘(𝑁 − 1)) + (𝐹‘𝑁))) | 
| 23 |   | oveq2 5930 | 
. . . . . . . . . 10
⊢ (𝑥 = 𝑍 → (𝑍 + 𝑥) = (𝑍 + 𝑍)) | 
| 24 |   | id 19 | 
. . . . . . . . . 10
⊢ (𝑥 = 𝑍 → 𝑥 = 𝑍) | 
| 25 | 23, 24 | eqeq12d 2211 | 
. . . . . . . . 9
⊢ (𝑥 = 𝑍 → ((𝑍 + 𝑥) = 𝑥 ↔ (𝑍 + 𝑍) = 𝑍)) | 
| 26 |   | iseqid.1 | 
. . . . . . . . . 10
⊢ ((𝜑 ∧ 𝑥 ∈ 𝑆) → (𝑍 + 𝑥) = 𝑥) | 
| 27 | 26 | ralrimiva 2570 | 
. . . . . . . . 9
⊢ (𝜑 → ∀𝑥 ∈ 𝑆 (𝑍 + 𝑥) = 𝑥) | 
| 28 |   | iseqid.2 | 
. . . . . . . . 9
⊢ (𝜑 → 𝑍 ∈ 𝑆) | 
| 29 | 25, 27, 28 | rspcdva 2873 | 
. . . . . . . 8
⊢ (𝜑 → (𝑍 + 𝑍) = 𝑍) | 
| 30 | 29 | adantr 276 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → (𝑍 + 𝑍) = 𝑍) | 
| 31 |   | eluzp1m1 9625 | 
. . . . . . . 8
⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈
(ℤ≥‘(𝑀 + 1))) → (𝑁 − 1) ∈
(ℤ≥‘𝑀)) | 
| 32 | 17, 31 | sylan 283 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → (𝑁 − 1) ∈
(ℤ≥‘𝑀)) | 
| 33 |   | iseqid.5 | 
. . . . . . . 8
⊢ ((𝜑 ∧ 𝑥 ∈ (𝑀...(𝑁 − 1))) → (𝐹‘𝑥) = 𝑍) | 
| 34 | 33 | adantlr 477 | 
. . . . . . 7
⊢ (((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) ∧ 𝑥 ∈ (𝑀...(𝑁 − 1))) → (𝐹‘𝑥) = 𝑍) | 
| 35 | 28 | adantr 276 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → 𝑍 ∈ 𝑆) | 
| 36 | 30, 32, 34, 35, 20, 21 | seq3id3 10616 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → (seq𝑀( + , 𝐹)‘(𝑁 − 1)) = 𝑍) | 
| 37 | 36 | oveq1d 5937 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → ((seq𝑀( + , 𝐹)‘(𝑁 − 1)) + (𝐹‘𝑁)) = (𝑍 + (𝐹‘𝑁))) | 
| 38 |   | oveq2 5930 | 
. . . . . . 7
⊢ (𝑥 = (𝐹‘𝑁) → (𝑍 + 𝑥) = (𝑍 + (𝐹‘𝑁))) | 
| 39 |   | id 19 | 
. . . . . . 7
⊢ (𝑥 = (𝐹‘𝑁) → 𝑥 = (𝐹‘𝑁)) | 
| 40 | 38, 39 | eqeq12d 2211 | 
. . . . . 6
⊢ (𝑥 = (𝐹‘𝑁) → ((𝑍 + 𝑥) = 𝑥 ↔ (𝑍 + (𝐹‘𝑁)) = (𝐹‘𝑁))) | 
| 41 | 27 | adantr 276 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → ∀𝑥 ∈ 𝑆 (𝑍 + 𝑥) = 𝑥) | 
| 42 |   | iseqid.4 | 
. . . . . . 7
⊢ (𝜑 → (𝐹‘𝑁) ∈ 𝑆) | 
| 43 | 42 | adantr 276 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → (𝐹‘𝑁) ∈ 𝑆) | 
| 44 | 40, 41, 43 | rspcdva 2873 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → (𝑍 + (𝐹‘𝑁)) = (𝐹‘𝑁)) | 
| 45 | 22, 37, 44 | 3eqtrd 2233 | 
. . . 4
⊢ ((𝜑 ∧ 𝑁 ∈ (ℤ≥‘(𝑀 + 1))) → (seq𝑀( + , 𝐹)‘𝑁) = (𝐹‘𝑁)) | 
| 46 | 45 | ex 115 | 
. . 3
⊢ (𝜑 → (𝑁 ∈ (ℤ≥‘(𝑀 + 1)) → (seq𝑀( + , 𝐹)‘𝑁) = (𝐹‘𝑁))) | 
| 47 |   | uzp1 9635 | 
. . . 4
⊢ (𝑁 ∈
(ℤ≥‘𝑀) → (𝑁 = 𝑀 ∨ 𝑁 ∈ (ℤ≥‘(𝑀 + 1)))) | 
| 48 | 1, 47 | syl 14 | 
. . 3
⊢ (𝜑 → (𝑁 = 𝑀 ∨ 𝑁 ∈ (ℤ≥‘(𝑀 + 1)))) | 
| 49 | 15, 46, 48 | mpjaod 719 | 
. 2
⊢ (𝜑 → (seq𝑀( + , 𝐹)‘𝑁) = (𝐹‘𝑁)) | 
| 50 |   | eqidd 2197 | 
. 2
⊢ ((𝜑 ∧ 𝑘 ∈ (ℤ≥‘(𝑁 + 1))) → (𝐹‘𝑘) = (𝐹‘𝑘)) | 
| 51 | 1, 49, 8, 9, 10, 50 | seq3feq2 10568 | 
1
⊢ (𝜑 → (seq𝑀( + , 𝐹) ↾
(ℤ≥‘𝑁)) = seq𝑁( + , 𝐹)) |