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Proof of the Modulo 4 Conjecture for OEIS A141117 and of the Parity Conjecture for OEIS A091713

Year: 2026
Type: preprint
Abstract: Let 𝐹(π‘₯) be the ordinary generating function of OEIS A091713, determined by 𝐹(π‘₯) = π‘₯ + π‘₯𝐹◦3(π‘₯),and let 𝐴(π‘₯) = 𝐹◦2(π‘₯), the ordinary generating function of OEIS A141117. We prove that every coefficientof 𝐹 is odd and that, for 𝑛 > 1, the coefficient π‘Ž(𝑛) = [π‘₯𝑛] 𝐴(π‘₯) is divisible by 4 exactly when 3 | 𝑛, whileπ‘Ž(𝑛) ≑ 2 (mod 4) otherwise. The argument is entirely within rings of formal power series.1 Statement and conventionsLet 𝐹(π‘₯) ∈ π‘₯Z[[π‘₯]] be the ordinary generating function of OEIS A091713. Its defining fu
Author: Yuan, Chi
Language: English
Open Access status: green
OpenAlex ID: W7203947899
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