English

Radically weakening the Lehmer and Carmichael conditions

Number Theory 2013-07-31 v1

Abstract

Lehmer's totient problem asks if there exist composite integers n satisfying the condition phi(n)|(n-1), (where phi is the Euler-phi function) while Carmichael numbers satisfy the weaker condition lambda(n)|(n-1) (where lambda is the Carmichael universal exponent function). We weaken the condition further, looking at those composite n where each prime divisor of phi(n) also divides n-1. (So rad(phi(n))|(n-1).) While these numbers appear to be far more numerous than the Carmichael numbers, we show that their distribution has the same rough upper bound as that of the Carmichael numbers, a bound which is heuristically tight.

Keywords

Cite

@article{arxiv.1210.2001,
  title  = {Radically weakening the Lehmer and Carmichael conditions},
  author = {Nathan McNew},
  journal= {arXiv preprint arXiv:1210.2001},
  year   = {2013}
}

Comments

10 pages

R2 v1 2026-06-21T22:17:27.745Z