English

Prime-bounded subwords

History and Overview 2019-12-19 v1

Abstract

In the number 373373 all subwords (33, 77, 3737, 7373, and 373373) are prime. Similarly, in 97199719 all subwords are divisible by at most one prime. And similarly again in 73197979137319797913 all subwords are divisible by at most two primes. These are the largest integers with their respective properties. We show for any k1k\ge 1 there are only finitely many integers having subwords divisible by at most kk primes. In fact, we show for any BB and dd coprime that nn contains a base-BB subword divisible by dd if n>Bdn>B^d. So as example consequence, past a certain point every prime contains a subword divisible by say 1000000000710000000007.

Keywords

Cite

@article{arxiv.1912.08598,
  title  = {Prime-bounded subwords},
  author = {Onno M. Cain},
  journal= {arXiv preprint arXiv:1912.08598},
  year   = {2019}
}

Comments

3 pages, 1 figure, 1 table

R2 v1 2026-06-23T12:49:42.843Z