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.

A327963 If A327928(n) > 0, a(n) = A276086(n), otherwise a(n) = A003415(n).

Original entry on oeis.org

0, 1, 1, 9, 1, 5, 1, 15, 6, 7, 1, 25, 1, 9, 150, 225, 1, 21, 1, 375, 10, 13, 1, 625, 10, 15, 3750, 5625, 1, 31, 1, 21, 14, 19, 126, 35, 1, 21, 210, 315, 1, 41, 1, 525, 39, 25, 1, 875, 14, 45, 5250, 7875, 1, 4375, 8750, 13125, 22, 31, 1, 49, 1, 33, 51, 441, 18, 61, 1, 735, 26, 59, 1, 1225, 1, 39, 55, 11025, 18, 71, 1, 18375, 36750, 43, 1, 30625, 22, 45
Offset: 1

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Author

Antti Karttunen, Oct 07 2019

Keywords

Comments

After zero, sequence contains only terms of A048103.

Crossrefs

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A129251(n) = { my(f = factor(n)); sum(k=1, #f~, (f[k, 2]>=f[k, 1])); };
    A276086(n) = { my(i=0,m=1,pr=1,nextpr); while((n>0),i=i+1; nextpr = prime(i)*pr; if((n%nextpr),m*=(prime(i)^((n%nextpr)/pr));n-=(n%nextpr));pr=nextpr); m; };
    A327963(n) = if(1==n,0,my(u=A003415(n)); if(!A129251(u),u,A276086(n)));

Formula

If A327928(n) > 0 [when n is one of the terms in A327929], then a(n) = A276086(n), otherwise a(n) = A003415(n).
For n > 1, a(n) = A276086(A327964(n)).