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.

A336852 a(n) = sigma(A003961(n)) - sigma(n).

Original entry on oeis.org

0, 1, 2, 6, 2, 12, 4, 25, 18, 14, 2, 50, 4, 24, 24, 90, 2, 85, 4, 62, 40, 20, 6, 180, 26, 30, 116, 100, 2, 120, 6, 301, 36, 26, 48, 312, 4, 36, 52, 230, 2, 192, 4, 98, 170, 48, 6, 602, 76, 135, 48, 136, 6, 504, 40, 360, 64, 38, 2, 456, 6, 56, 268, 966, 60, 192, 4, 134, 84, 240, 2, 1045, 6, 54, 218, 172, 72, 264, 4, 782
Offset: 1

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Author

Antti Karttunen, Aug 05 2020

Keywords

Comments

Inverse Möbius transform of A336853(n) = (A003961(n) - n).

Crossrefs

Cf. A001105 (positions of odd terms), A001359 (positions of 2's).

Programs

  • PARI
    A003961(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
    A336852(n) = (sigma(A003961(n)) - sigma(n));
    
  • PARI
    A336852(n) = sumdiv(n,d,A003961(d)-d);

Formula

a(n) = Sum_{d|n} (A003961(d)-d).
a(n) = A003973(n) - A000203(n) = A000203(A003961(n)) - A000203(n).
a(n) = A336851(n) + A286385(n).