English

Divisibility of the central binomial coefficient $\binom{2n}{n}$

Number Theory 2021-06-24 v2 Combinatorics

Abstract

We show that for every fixed N\ell\in\mathbb{N}, the set of nn with n(2nn)n^\ell|\binom{2n}{n} has a positive asymptotic density cc_\ell, and we give an asymptotic formula for cc_\ell as \ell\to \infty. We also show that #{nx,(n,(2nn))=1}cx/logx\# \{n\le x, (n,\binom{2n}{n})=1 \} \sim cx/\log x for some constant cc. One novelty is a method to capture the effect of large prime factors of integers in general sequences.

Keywords

Cite

@article{arxiv.1909.03903,
  title  = {Divisibility of the central binomial coefficient $\binom{2n}{n}$},
  author = {Kevin Ford and Sergei Konyagin},
  journal= {arXiv preprint arXiv:1909.03903},
  year   = {2021}
}

Comments

v2. 27 pages. To appear in Trans. Amer. Math. Soc. Incorporates suggestions of the referee, plus new tables of numerical data

R2 v1 2026-06-23T11:09:49.859Z