cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A345002 Numbers k such that A345001(k)/A342001(k) is a positive natural number and a divisor of k.

Original entry on oeis.org

6, 28, 171, 496, 8128, 478800, 32317272, 33550336
Offset: 1

Views

Author

Antti Karttunen, Jun 05 2021

Keywords

Crossrefs

Cf. A000396 (subsequence), A003415, A003557, A342001, A345001.
Cf. also A344755.

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A003557(n) = (n/factorback(factorint(n)[, 1]));
    isA345002(n) = if(1==n,0,my(d=A003415(n), s=sigma(n)+d-(n+n), r=s/(d/A003557(n))); (r>0&&1==denominator(r)&&!(n%r)));