English

Some Extensions to Touchard's Theorem on Odd Perfect Numbers

Number Theory 2017-09-18 v1

Abstract

The multiplicative structure of an odd perfect number nn, if any, is n=παM2n=\pi^\alpha M^2, where π\pi is prime, gcd(π,M)=1\gcd(\pi,M)=1 and πα1(mod4)\pi\equiv \alpha\equiv1\pmod{4}. An additive structure of nn, established by Touchard, is that "(n9(mod36))\bigl(n\equiv 9\pmod{36}\bigr ) OR (n1(mod12))\bigl (n\equiv1\pmod{12}\bigr )". A first extension of Touchard's result is that the proposition "(nx2(mod4x2))\bigl(n\equiv x^2\pmod{4 x^2}\bigr ) OR (nπ1(mod4x))\bigl (n\equiv \pi\equiv1\pmod{4 x}\bigr )" holds for x=3x=3 (the extension is due to the fact that the second congruence contains also π\pi). We further extend the proof to x=α+2x=\alpha+2, α+2\alpha+2 prime, with the restriction that the congruence modulo 4x4 x does not include nn. Besides, we note that the first extension of Touchard's result holds also with an exclusive disjunction, so that π1(mod12)\pi\equiv 1\pmod{12} is a sufficient condition because 3n3\nmid n.

Keywords

Cite

@article{arxiv.1709.05286,
  title  = {Some Extensions to Touchard's Theorem on Odd Perfect Numbers},
  author = {Paolo Starni},
  journal= {arXiv preprint arXiv:1709.05286},
  year   = {2017}
}

Comments

5 pages

R2 v1 2026-06-22T21:44:36.790Z