English

Hankel-type determinants for some combinatorial sequences

Combinatorics 2018-08-03 v4

Abstract

In this paper we confirm several conjectures of Z.-W. Sun on Hankel-type determinants for some combinatorial sequences including Franel numbers, Domb numbers and Ap\'ery numbers. For any nonnegative integer nn, define \begin{gather*}f_n:=\sum_{k=0}^n\binom nk^3,\ D_n:=\sum_{k=0}^n\binom nk^2\binom{2k}k\binom{2(n-k)}{n-k}, b_n:=\sum_{k=0}^n\binom nk^2\binom{n+k}k,\ A_n:=\sum_{k=0}^n\binom nk^2\binom{n+k}k^2. \end{gather*} For n=0,1,2,n=0,1,2,\ldots, we show that 6nfi+j0i,jn6^{-n}|f_{i+j}|_{0\leq i,j\leq n} and 12nDi+j0i,jn12^{-n}|D_{i+j}|_{0\le i,j\le n} are positive odd integers, and 10nbi+j0i,jn10^{-n}|b_{i+j}|_{0\leq i,j\leq n} and 24nAi+j0i,jn24^{-n}|A_{i+j}|_{0\leq i,j\leq n} are always integers.

Keywords

Cite

@article{arxiv.1609.06810,
  title  = {Hankel-type determinants for some combinatorial sequences},
  author = {Bao-Xuan Zhu and Zhi-Wei Sun},
  journal= {arXiv preprint arXiv:1609.06810},
  year   = {2018}
}

Comments

13 pages, final published version

R2 v1 2026-06-22T15:57:24.732Z