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# Divisibility properties of sporadic Apéry-like numbers

Divisibility properties of sporadic Apéry-like numbers
Amita Malik, Armin Straub — Research in Number Theory — Volume 2, Number 1, 2016, Pages 1-26

## Abstract

In 1982, Gessel showed that the Apéry numbers associated to the irrationality of $$\zeta(3)$$ satisfy Lucas congruences. Our main result is to prove corresponding congruences for all sporadic Apéry-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 $$s_{18}$$ and $$(\eta)$$ 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 $$8$$, a special property which they share with the Apéry numbers. We also investigate primes which do not divide any term of a given Apéry-like sequence.

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## BibTeX

@article{lucascongruences-2016,
author = {Amita Malik and Armin Straub},
title = {Divisibility properties of sporadic {A}p\'ery-like numbers},
journal = {Research in Number Theory},
year = {2016},
volume = {2},
number = {1},
pages = {1--26},
doi = {10.1007/s40993-016-0036-8},
}