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.

A340367 Dirichlet inverse of sequence b(n) = 1-A318833(n).

Original entry on oeis.org

-1, 0, 0, 2, 0, 7, 0, 6, 6, 13, 0, 13, 0, 19, 22, 10, 0, 19, 0, 23, 32, 31, 0, -3, 20, 37, 24, 33, 0, 21, 0, 6, 52, 49, 58, -36, 0, 55, 62, -9, 0, 29, 0, 53, 52, 67, 0, -87, 42, 53, 82, 63, 0, -29, 94, -15, 92, 85, 0, -219, 0, 91, 74, -22, 112, 45, 0, 83, 112, 45, 0, -257, 0, 109, 82, 93, 136, 53, 0, -165, 42, 121
Offset: 1

Views

Author

Antti Karttunen, Jan 05 2021

Keywords

Crossrefs

Cf. also A340140, A340197 for similar definitions.

Programs

  • PARI
    up_to = 65537;
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA023900(n) = factorback(apply(p -> 1-p, factor(n)[, 1]));
    A318833(n) = (n+A023900(n));
    v340367 = DirInverseCorrect(vector(up_to, n, 1-A318833(n)));
    A340367(n) = v340367[n];
    
  • PARI
    \\ Or as:
    A340367(n) = if(1==n, -1, sumdiv(n, d, if(dA318833(n/d))*A340367(d), 0)));

Formula

a(1) = -1, for n > 1, a(n) = Sum_{d|n, dA318833(n/d)) * a(d).