English

Divisibility properties of sporadic Ap\'ery-like numbers

Number Theory 2015-08-04 v1 Combinatorics

Abstract

In 1982, Gessel showed that the Ap\'ery numbers associated to the irrationality of ζ(3)\zeta(3) satisfy Lucas congruences. Our main result is to prove corresponding congruences for all sporadic Ap\'ery-like sequences. In several cases, we are able to employ approaches due to McIntosh, Samol--van Straten and Rowland--Yassawi to establish these congruences. However, for the sequences often labeled s18s_{18} and (η)(\eta) we require a finer analysis. As an application, we investigate modulo which numbers these sequences are periodic. In particular, we show that the Almkvist--Zudilin numbers are periodic modulo 88, a special property which they share with the Ap\'ery numbers. We also investigate primes which do not divide any term of a given Ap\'ery-like sequence.

Keywords

Cite

@article{arxiv.1508.00297,
  title  = {Divisibility properties of sporadic Ap\'ery-like numbers},
  author = {Amita Malik and Armin Straub},
  journal= {arXiv preprint arXiv:1508.00297},
  year   = {2015}
}

Comments

30 pages, 1 figure