English

$q$-Congruences for Z.-W. Sun's generalized polynomials $w^{(\alpha)}_k(x)$

Number Theory 2025-07-08 v1 Combinatorics

Abstract

In 2022, Z.-W. Sun defined \begin{equation*} w_k^{(\alpha)}{(x)}=\sum_{j=1}^{k}w(k,j)^{\alpha}x^{j-1}, \end{equation*} where k,αk,\alpha are positive integers and w(k,j)=1j(k1j1)(k+jj1)w(k,j)=\frac{1}{j}\binom{k-1}{j-1}\binom{k+j}{j-1}. Let (x)0=1(x)_{0}=1 and (x)n=x(x+1)(x+n1)(x)_{n}=x(x+1)\cdots(x+n-1) for all n1n\geq 1. In this paper, it is proved by qq-congruences that for any positive integers α,β,m,n,r{\alpha,\beta, m,n,r}, we have \begin{equation*} \frac{(2,n)}{n(n+1)(n+2)}\sum_{k=1}^{n}k^r(k+1)^r(2k+1)w_{k}^{(\alpha)}(x)^{m}\in\mathbb{Z}[x], \end{equation*} \begin{equation*} \frac{(2,n)}{n(n+1)(n+2)}\sum_{k=1}^{n}(-1)^{k}k^r(k+1)^r(2k+1) w_{k}^{(\alpha)}(x)^{m}\in\mathbb{Z}[x], \end{equation*} and \begin{equation*} \frac{2}{[n,n+1,\cdots,n+2\beta+1]}\sum_{k=1}^{n}(k)_{\beta}^r(k+\beta+1)_{\beta}^r(k+\beta) \prod_{i=0}^{2\beta-1}w_{k+i}^{(\alpha)}(x)^m\in\mathbb{Z}[x], \end{equation*} where [n,n+1,,n+2β+1][n,n+1,\cdots,n+2\beta+1] is the least common multiple of nn, n+1n+1, \cdots, n+2β+1n+2\beta+1. Taking r=β=1r=\beta=1 above will confirm some of Z.-W. Sun's conjectures.

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Cite

@article{arxiv.2507.04653,
  title  = {$q$-Congruences for Z.-W. Sun's generalized polynomials $w^{(\alpha)}_k(x)$},
  author = {Lin-Yue Li and Rong-Hua Wang},
  journal= {arXiv preprint arXiv:2507.04653},
  year   = {2025}
}