English

On the binomial transforms of Ap\'ery-like sequences

Number Theory 2024-06-27 v1 Combinatorics

Abstract

In the proof of the irrationality of ζ(3)\zeta(3) and ζ(2)\zeta(2), Ap\'ery defined two integer sequences through 33-term recurrences, which are known as the famous Ap\'ery numbers. Zagier, Almkvist--Zudilin and Cooper successively introduced the other 1313 sporadic sequences through variants of Ap\'ery's 33-term recurrences. All of the 1515 sporadic sequences are called Ap\'ery-like sequences. Motivated by Gessel's congruences mod 2424 for the Ap\'ery numbers, we investigate the congruences in the form unαn(modNα) (αZ,NαN+)u_n\equiv \alpha^n \pmod{N_{\alpha}}~(\alpha\in \mathbb{Z},N_{\alpha}\in \mathbb{N}^{+}) for all of the 1515 Ap\'ery-like sequences {un}n0\{u_n\}_{n\ge 0}. Let NαN_{\alpha} be the largest positive integer such that unαn(modNα)u_n\equiv \alpha^n \pmod{N_{\alpha}} for all non-negative integers nn. We determine the values of max{NααZ}\max\{N_{\alpha}|\alpha \in \mathbb{Z}\} for all of the 1515 Ap\'ery-like sequences {un}n0\{u_n\}_{n\ge 0}.The binomial transforms of Ap\'ery-like sequences provide us a unified approach to this type of congruences for Ap\'ery-like sequences.

Keywords

Cite

@article{arxiv.2406.18059,
  title  = {On the binomial transforms of Ap\'ery-like sequences},
  author = {Ji-Cai Liu},
  journal= {arXiv preprint arXiv:2406.18059},
  year   = {2024}
}

Comments

19 pages

R2 v1 2026-06-28T17:19:27.106Z