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.

A378436 Inverse Möbius transform of A033630, where A033630 is the number of partitions of n into distinct divisors of n.

Original entry on oeis.org

1, 2, 2, 3, 2, 5, 2, 4, 3, 4, 2, 9, 2, 4, 4, 5, 2, 9, 2, 7, 4, 4, 2, 16, 3, 4, 4, 7, 2, 12, 2, 6, 4, 4, 4, 21, 2, 4, 4, 12, 2, 11, 2, 6, 6, 4, 2, 28, 3, 6, 4, 6, 2, 14, 4, 11, 4, 4, 2, 53, 2, 4, 6, 7, 4, 11, 2, 6, 4, 8, 2, 60, 2, 4, 6, 6, 4, 10, 2, 20, 5, 4, 2, 43, 4, 4, 4, 9, 2, 41, 4, 6, 4, 4, 4, 51, 2, 6, 6, 12
Offset: 1

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Author

Antti Karttunen, Nov 26 2024

Keywords

Comments

The odd bisection differs from A099774 (the odd bisection of A000005) apparently in the positions given by A005231 (odd abundant numbers): 945, 1575, 2205, 2835, 3465, ...

Crossrefs

Cf. A000005, A005231, A033630, A099774, A378438 (Dirichlet inverse).

Programs

  • PARI
    A033630(n) = if(!n, 1, my(p=1); fordiv(n, d, p *= (1 + 'x^d)); polcoeff(p, n));
    A378436(n) = sumdiv(n,d,A033630(d));

Formula

a(n) = Sum_{d|n} A033630(d).