A047682 a(n) = 4^(2*n)*(4^(2*n)-1)*Bernoulli(2*n)/(2*n).

20, -544, 66560, -17895424, 8329625600, -5937093935104, 6004799480791040, -8176700159200067584, 14421891569272362106880, -31983597922505761818148864, 87107695717210805652024197120, -285816431841945942589104606674944, 1112035502745012017553352712530165760

Offset: 1

Author

N. J. A. Sloane

Keywords

• sign

References

• J. W. Milnor and J. D. Stasheff, Characteristic Classes, Princeton, 1974, p. 283.

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..100
• Index entries for sequences related to Bernoulli numbers.

Crossrefs

Column 3 of A241066.

Row sums of even-indexed rows of A211233.

Programs

Mathematica

f[n_]:=Module[{c=2n,x},x=4^c;(x(x-1)BernoulliB[c])/c]; Array[f,20] (* Harvey P. Dale, Feb 19 2013 *)

PARI

a(n) = 4^(2*n)*(4^(2*n)-1)*bernfrac(2*n)/(2*n) \\ Andrew Howroyd, May 18 2020

Extensions

Offset corrected and terms a(13) and beyond from Andrew Howroyd, May 18 2020