English

A natural prime-generating recurrence

Number Theory 2008-07-23 v3

Abstract

For the sequence defined by a(n) = a(n-1) + gcd(n, a(n-1)) with a(1) = 7 we prove that a(n) - a(n-1) takes on only 1s and primes, making this recurrence a rare "naturally occurring" generator of primes. Toward a generalization of this result to an arbitrary initial condition, we also study the limiting behavior of a(n)/n and a transience property of the evolution.

Keywords

Cite

@article{arxiv.0710.3217,
  title  = {A natural prime-generating recurrence},
  author = {Eric S. Rowland},
  journal= {arXiv preprint arXiv:0710.3217},
  year   = {2008}
}

Comments

11 pages, 2 figures; published version

R2 v1 2026-06-21T09:32:54.240Z