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.

A068219 Denominators of coefficients in log(1+x)*(1+x)^(1/3) power series.

Original entry on oeis.org

3, 3, 9, 3, 15, 9, 21, 6, 27, 15, 33, 9, 39, 21, 45, 12, 51, 27, 57, 15, 63, 33, 69, 18, 75, 39, 81, 21, 87, 45, 93, 24, 99, 51, 105, 27, 111, 57, 117, 30, 123, 63, 129, 33, 135, 69, 141, 36, 147, 75, 153, 39, 159, 81, 165, 42, 171, 87, 177, 45, 183, 93, 189, 48, 195, 99
Offset: 1

Views

Author

Benoit Cloitre, Mar 30 2002

Keywords

Comments

log(1+x)*(1+x)^(1/3) = (-4)*sum(k=>1,(-x)^k/(3k))

Programs

  • Mathematica
    fn[n_]:=Module[{m=Mod[n,4]},Which[OddQ[m],3n,m==2,3 n/2,True,3 n/4]]; Array[fn,70] (* Harvey P. Dale, Sep 18 2012 *)

Formula

a(n) = 3*n if n==1 or 3 (mod 4), a(n) = 3*n/2 if n==2 (mod 4), a(n) = 3*n/4 if n==0 (mod 4).
a(n) = 3*A060819(n). - Mitch Harris, Jun 29 2005