English

The most probable order of a random permutation

Combinatorics 2025-10-14 v1 Group Theory

Abstract

Given positive integers nn and mm, let pn(m)p_n(m) be the probability that a uniform random permutation of [n][n] has order exactly mm. We show that, as nn \to \infty, the maximum of pn(m)p_n(m) over all mm is asymptotic to 1/n1/n, the probability of an nn-cycle. Furthermore, for sufficiently large nn, we show that the maximum is attained precisely if mm is the least positive integer divisible by all positive integers less than or equal to nmn-m. This answers a question of Acan, Burnette, Eberhard, Schmutz and Thomas, originally attributed to work of Erd\H{o}s and Tur\'an from 1968.

Keywords

Cite

@article{arxiv.2510.11698,
  title  = {The most probable order of a random permutation},
  author = {Adrian Beker},
  journal= {arXiv preprint arXiv:2510.11698},
  year   = {2025}
}

Comments

8 pages

R2 v1 2026-07-01T06:34:34.529Z