A076574 - OEIS

%I #5 Mar 30 2012 18:39:10

%S 1,683,557875,1633383863,9367236055495,87201869442139043,

%T 1193374352393955942715,22530375500983985686992623,

%U 560996326873703660609079627535,17810524140784329468678138258776603

%N a(0)=1 if n>0 a(n)=(-1)^(n+1)/(2n+1)*sum(k=0,n,4^(6k)*B(2k)*C(2n+1,2k)) where B(k) denotes the k-th Bernoulli number.

%o (PARI) a(n)=sum(i=0,n,4^(6*i)*bernfrac(2*i)*binomial(2*n+1,2*i))

%K nonn

%O 0,2

%A _Benoit Cloitre_, Oct 19 2002