A069992 (-1)^(n+1)/3*sum(k=1,2n,C(2n+1,k)*B(k)*6^k) where C(n,k) are the binomial coefficients, B(k) the Bernoulli numbers.

3, 57, 2123, 138609, 13883283, 1974243241, 378027128283, 93761532169953, 29240923237509923, 11199084302796542745, 5167442341466021937003, 2827285169201754895553617, 1809878752362221218378054323

Offset

1,1

Links

Table of n, a(n) for n=1..13.

Prog

(PARI) for(n=1, 25, print1(-(-1)^n*sum(i=1, 2*n, binomial(2*n+1, i)*bernfrac(i)*6^i)/3, ", "))

Crossrefs

Sequence in context: A254570 A308404 A009723 * A012196 A012090 A210674

Adjacent sequences: A069989 A069990 A069991 * A069993 A069994 A069995

Keyword

easy,nonn

Author

Benoit Cloitre, May 01 2002

Status

approved