中文

A Flanking Pattern in a Sum-of-Divisors Congruence

数论 2025-12-23 v1

摘要

We consider composite nn satisfying the congruence nσk(n)2(modϕ(n)),n \cdot \sigma_k(n) \equiv 2 \pmod{\phi(n)}, and show a "flanking" structure: 1414 appears in both Sk1S_{k-1} and Sk+1S_{k+1} whenever certain values of nn appear in SkS_k; and, moreover, 1414 is the only (nontrivial) case of this property. Along the way, we derive a new characterization of the nn that appear in the sets SkS_{k}.

引用

@article{arxiv.2512.18424,
  title  = {A Flanking Pattern in a Sum-of-Divisors Congruence},
  author = {Scott Duke Kominers},
  journal= {arXiv preprint arXiv:2512.18424},
  year   = {2025}
}

备注

8 pages, 2 tables, plus source code appendix