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.

A327800 Expansion of 1 / (1 + Sum_{i>=1, j>=1} x^(i*prime(j))).

Original entry on oeis.org

1, 0, -1, -1, 0, 1, 0, 0, 1, 1, -2, -3, 0, 4, 2, -3, 0, 4, -1, -10, -5, 12, 13, -6, -12, 7, 9, -20, -28, 23, 57, 1, -59, -18, 51, -5, -93, 1, 176, 93, -189, -188, 131, 183, -191, -220, 370, 525, -347, -902, 44, 973, 64, -1071, 171, 1881, 156, -2974, -1537
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 25 2019

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 58; CoefficientList[Series[1/(1 + Sum[x^Prime[k]/(1 - x^Prime[k]), {k, 1, nmax}]), {x, 0, nmax}], x]
    a[0] = 1; a[n_] := a[n] = -Sum[PrimeNu[k] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 58}]

Formula

G.f.: 1 / (1 + Sum_{k>=1} x^prime(k) / (1 - x^prime(k))).
a(0) = 1; a(n) = -Sum_{k=1..n} A001221(k) * a(n-k).