A069988 - OEIS

A069988

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

%I #5 Mar 30 2012 18:38:58

%S 0,1,8,135,3386,120469,5767884,357666403,27886211102,2670067220337,

%T 308003491726640,42129829536116671,6742323657098884098,

%U 1248097176923675241805,264614795104954119229076

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

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

%K easy,nonn

%O 1,3

%A _Benoit Cloitre_, May 01 2002