A069685 Denominators of coefficients in -log(1+x)log(1-x) power series.

1, 12, 180, 1680, 12600, 166320, 2522520, 576576, 22054032, 465585120, 2560718160, 64250746560, 348024877200, 1124388064800, 4990906206000, 165032631878400, 350694342741600, 2599263952084800, 101515697684200800

Offset: 1

Author

Benoit Cloitre, May 03 2002

Keywords

• easy
• frac
• nonn

Crossrefs

Cf. A049281, A076100.

Programs

PARI

my(x='x+O('x^50), v=Vec(-log(1+x)*log(1-x))); apply(denominator, vector(#v\2, k, v[2*k-1])) \\ Michel Marcus, Feb 16 2021

Formula

a(n) = n*A076100(n) (conjectured). - F. Chapoton, Nov 09 2009