English

Matchable numbers

Number Theory 2026-05-26 v2 Combinatorics

Abstract

We say a natural number nn is matchable if there is a bijection from the set of τ(n)\tau(n) divisors of nn to the set {1,2,,τ(n)}\{1,2,\dots,\tau(n)\}, where corresponding numbers are relatively prime. We show that the set of matchable numbers has an asymptotic density, which we compute, and we show that every squarefree number is matchable. We also present some related unsolved problems.

Keywords

Cite

@article{arxiv.2604.05304,
  title  = {Matchable numbers},
  author = {Nathan McNew and Carl Pomerance},
  journal= {arXiv preprint arXiv:2604.05304},
  year   = {2026}
}

Comments

Code to generate tables is included as an ancillary file

R2 v1 2026-07-01T11:56:25.581Z