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.

A323905 a(n) = A156552(n) - A048675(n).

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 4, 2, 4, 0, 7, 0, 8, 4, 11, 0, 8, 0, 13, 8, 16, 0, 18, 4, 32, 8, 25, 0, 14, 0, 26, 16, 64, 8, 21, 0, 128, 32, 32, 0, 26, 0, 49, 14, 256, 0, 41, 8, 16, 64, 97, 0, 22, 16, 60, 128, 512, 0, 35, 0, 1024, 26, 57, 32, 50, 0, 193, 256, 28, 0, 48, 0, 2048, 16, 385, 16, 98, 0, 71, 22, 4096, 0, 63, 64, 8192, 512, 116, 0, 36, 32, 769, 1024
Offset: 1

Views

Author

Antti Karttunen, Feb 12 2019

Keywords

Crossrefs

Cf. A048675, A156552, A323906 (rgs-transform).

Programs

  • PARI
    A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; }; \\ From A048675
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A156552(n) = if(1==n, 0, if(!(n%2), 1+(2*A156552(n/2)), 2*A156552(A064989(n))));
    A323905(n) = (A156552(n) - A048675(n));

Formula

a(n) = A156552(n) - A048675(n).