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.

A344024 a(n) = A003415(A001615(n)).

Original entry on oeis.org

0, 1, 4, 5, 5, 16, 12, 16, 16, 21, 16, 44, 9, 44, 44, 44, 21, 60, 24, 60, 80, 60, 44, 112, 31, 41, 60, 112, 31, 156, 80, 112, 112, 81, 112, 156, 21, 92, 92, 156, 41, 272, 48, 156, 156, 156, 112, 272, 92, 123, 156, 124, 81, 216, 156, 272, 176, 123, 92, 384, 33, 272, 272, 272, 124, 384, 72, 216, 272, 384, 156, 384, 39, 101
Offset: 1

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Author

Antti Karttunen, May 09 2021

Keywords

Comments

The first nonsquarefree numbers for which this sequence coincides with A342925 are 868, 920, 952, 4260, 4452, 4692, 5060, 5172, ...

Crossrefs

Cf. also A342925.

Programs

  • Mathematica
    {0}~Join~Array[If[# < 2, 0, # Total[#2/#1 & @@@ FactorInteger[#]]] &[# Product[1 + 1/p, {p, FactorInteger[#][[All, 1]]}] ] &, 73, 2] (* Michael De Vlieger, May 16 2021 *)
  • PARI
    A001615(n) = if(1==n,n, my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1))); \\ After code in A001615
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A344024(n) = A003415(A001615(n));

Formula

a(A005117(n)) = A342925(A005117(n)) for all n.