A069989 (-1)^(n+1)/2*sum(k=1,2n,C(2n+1,k)*B(k)*4^k) where C(n,k) are the binomial coefficients, B(k) the Bernoulli numbers.

1, 13, 213, 6233, 277865, 17567973, 1495207357, 164827853233, 22846356916689, 3888897476494013, 797512055521085861, 193931677044463586313, 55175478875457172546873, 18157764800352633049290133

Offset

1,2

Links

Table of n, a(n) for n=1..14.

Prog

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

Crossrefs

Sequence in context: A340431 A251093 A132542 * A140517 A096141 A218475

Adjacent sequences: A069986 A069987 A069988 * A069990 A069991 A069992

Keyword

easy,nonn

Author

Benoit Cloitre, May 01 2002

Status

approved