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Mirrors > Home > MPE Home > Th. List > sqoddm1div8z | Structured version Visualization version GIF version |
Description: A squared odd number minus 1 divided by 8 is an integer. (Contributed by AV, 19-Jul-2021.) |
Ref | Expression |
---|---|
sqoddm1div8z | ⊢ ((𝑁 ∈ ℤ ∧ ¬ 2 ∥ 𝑁) → (((𝑁↑2) − 1) / 8) ∈ ℤ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | odd2np1 15685 | . . 3 ⊢ (𝑁 ∈ ℤ → (¬ 2 ∥ 𝑁 ↔ ∃𝑘 ∈ ℤ ((2 · 𝑘) + 1) = 𝑁)) | |
2 | 1 | biimpa 479 | . 2 ⊢ ((𝑁 ∈ ℤ ∧ ¬ 2 ∥ 𝑁) → ∃𝑘 ∈ ℤ ((2 · 𝑘) + 1) = 𝑁) |
3 | eqcom 2827 | . . . 4 ⊢ (((2 · 𝑘) + 1) = 𝑁 ↔ 𝑁 = ((2 · 𝑘) + 1)) | |
4 | sqoddm1div8 13601 | . . . . . . 7 ⊢ ((𝑘 ∈ ℤ ∧ 𝑁 = ((2 · 𝑘) + 1)) → (((𝑁↑2) − 1) / 8) = ((𝑘 · (𝑘 + 1)) / 2)) | |
5 | 4 | adantll 712 | . . . . . 6 ⊢ ((((𝑁 ∈ ℤ ∧ ¬ 2 ∥ 𝑁) ∧ 𝑘 ∈ ℤ) ∧ 𝑁 = ((2 · 𝑘) + 1)) → (((𝑁↑2) − 1) / 8) = ((𝑘 · (𝑘 + 1)) / 2)) |
6 | mulsucdiv2z 15697 | . . . . . . 7 ⊢ (𝑘 ∈ ℤ → ((𝑘 · (𝑘 + 1)) / 2) ∈ ℤ) | |
7 | 6 | ad2antlr 725 | . . . . . 6 ⊢ ((((𝑁 ∈ ℤ ∧ ¬ 2 ∥ 𝑁) ∧ 𝑘 ∈ ℤ) ∧ 𝑁 = ((2 · 𝑘) + 1)) → ((𝑘 · (𝑘 + 1)) / 2) ∈ ℤ) |
8 | 5, 7 | eqeltrd 2912 | . . . . 5 ⊢ ((((𝑁 ∈ ℤ ∧ ¬ 2 ∥ 𝑁) ∧ 𝑘 ∈ ℤ) ∧ 𝑁 = ((2 · 𝑘) + 1)) → (((𝑁↑2) − 1) / 8) ∈ ℤ) |
9 | 8 | ex 415 | . . . 4 ⊢ (((𝑁 ∈ ℤ ∧ ¬ 2 ∥ 𝑁) ∧ 𝑘 ∈ ℤ) → (𝑁 = ((2 · 𝑘) + 1) → (((𝑁↑2) − 1) / 8) ∈ ℤ)) |
10 | 3, 9 | syl5bi 244 | . . 3 ⊢ (((𝑁 ∈ ℤ ∧ ¬ 2 ∥ 𝑁) ∧ 𝑘 ∈ ℤ) → (((2 · 𝑘) + 1) = 𝑁 → (((𝑁↑2) − 1) / 8) ∈ ℤ)) |
11 | 10 | rexlimdva 3283 | . 2 ⊢ ((𝑁 ∈ ℤ ∧ ¬ 2 ∥ 𝑁) → (∃𝑘 ∈ ℤ ((2 · 𝑘) + 1) = 𝑁 → (((𝑁↑2) − 1) / 8) ∈ ℤ)) |
12 | 2, 11 | mpd 15 | 1 ⊢ ((𝑁 ∈ ℤ ∧ ¬ 2 ∥ 𝑁) → (((𝑁↑2) − 1) / 8) ∈ ℤ) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 398 = wceq 1536 ∈ wcel 2113 ∃wrex 3138 class class class wbr 5059 (class class class)co 7149 1c1 10531 + caddc 10533 · cmul 10535 − cmin 10863 / cdiv 11290 2c2 11686 8c8 11692 ℤcz 11975 ↑cexp 13426 ∥ cdvds 15602 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1910 ax-6 1969 ax-7 2014 ax-8 2115 ax-9 2123 ax-10 2144 ax-11 2160 ax-12 2176 ax-ext 2792 ax-sep 5196 ax-nul 5203 ax-pow 5259 ax-pr 5323 ax-un 7454 ax-cnex 10586 ax-resscn 10587 ax-1cn 10588 ax-icn 10589 ax-addcl 10590 ax-addrcl 10591 ax-mulcl 10592 ax-mulrcl 10593 ax-mulcom 10594 ax-addass 10595 ax-mulass 10596 ax-distr 10597 ax-i2m1 10598 ax-1ne0 10599 ax-1rid 10600 ax-rnegex 10601 ax-rrecex 10602 ax-cnre 10603 ax-pre-lttri 10604 ax-pre-lttrn 10605 ax-pre-ltadd 10606 ax-pre-mulgt0 10607 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1083 df-3an 1084 df-tru 1539 df-ex 1780 df-nf 1784 df-sb 2069 df-mo 2621 df-eu 2653 df-clab 2799 df-cleq 2813 df-clel 2892 df-nfc 2962 df-ne 3016 df-nel 3123 df-ral 3142 df-rex 3143 df-reu 3144 df-rmo 3145 df-rab 3146 df-v 3493 df-sbc 3769 df-csb 3877 df-dif 3932 df-un 3934 df-in 3936 df-ss 3945 df-pss 3947 df-nul 4285 df-if 4461 df-pw 4534 df-sn 4561 df-pr 4563 df-tp 4565 df-op 4567 df-uni 4832 df-iun 4914 df-br 5060 df-opab 5122 df-mpt 5140 df-tr 5166 df-id 5453 df-eprel 5458 df-po 5467 df-so 5468 df-fr 5507 df-we 5509 df-xp 5554 df-rel 5555 df-cnv 5556 df-co 5557 df-dm 5558 df-rn 5559 df-res 5560 df-ima 5561 df-pred 6141 df-ord 6187 df-on 6188 df-lim 6189 df-suc 6190 df-iota 6307 df-fun 6350 df-fn 6351 df-f 6352 df-f1 6353 df-fo 6354 df-f1o 6355 df-fv 6356 df-riota 7107 df-ov 7152 df-oprab 7153 df-mpo 7154 df-om 7574 df-2nd 7683 df-wrecs 7940 df-recs 8001 df-rdg 8039 df-er 8282 df-en 8503 df-dom 8504 df-sdom 8505 df-pnf 10670 df-mnf 10671 df-xr 10672 df-ltxr 10673 df-le 10674 df-sub 10865 df-neg 10866 df-div 11291 df-nn 11632 df-2 11694 df-3 11695 df-4 11696 df-5 11697 df-6 11698 df-7 11699 df-8 11700 df-n0 11892 df-z 11976 df-uz 12238 df-seq 13367 df-exp 13427 df-dvds 15603 |
This theorem is referenced by: 2lgsoddprm 25990 |
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