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A new approach to odd perfect numbers via GCDs

Number Theory 2023-03-30 v1

Abstract

Let qkn2q^k n^2 be an odd perfect number with special prime qq. Define the GCDs G=gcd(σ(qk),σ(n2))G = \gcd\bigg(\sigma(q^k),\sigma(n^2)\bigg) H=gcd(n2,σ(n2))H = \gcd\bigg(n^2,\sigma(n^2)\bigg) and I=gcd(n,σ(n2)).I = \gcd\bigg(n,\sigma(n^2)\bigg). We prove that G×H=I2G \times H = I^2. (Note that it is trivial to show that GIG \mid I and IHI \mid H both hold.) We then compute expressions for G,H,G, H, and II in terms of σ(qk)/2,n,\sigma(q^k)/2, n, and gcd(σ(qk)/2,n)\gcd\bigg(\sigma(q^k)/2,n\bigg). Afterwards, we prove that if G=H=IG = H = I, then σ(qk)/2\sigma(q^k)/2 is not squarefree. Other natural and related results are derived further. Lastly, we conjecture that the set A={m:gcd(m,σ(m2))=gcd(m2,σ(m2))}\mathscr{A} = \{m : \gcd(m,\sigma(m^2))=\gcd(m^2,\sigma(m^2))\} has asymptotic density zero.

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Cite

@article{arxiv.2202.08116,
  title  = {A new approach to odd perfect numbers via GCDs},
  author = {Jose Arnaldo Bebita Dris},
  journal= {arXiv preprint arXiv:2202.08116},
  year   = {2023}
}

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9 pages