OFFSET
0,2
FORMULA
a(n) = (n+1)!^2*sum(m=1..n, 2^(n-2*m)*(-1)^((n-m)/2)*sum(l=0..m, 2^l*l!* C(m,l)*sum(k=0..n-2*m+l,(k!*stirling1(l+k,l)*stirling2(n-2*m+l,k))/ ((l+k)!*(n-2*m+l)!)))*bernoulli(m)/(m)!), n>0, a(0)=1.
PROG
(Maxima) a(n):=if n=0 then 1 else (n+1)!^2*sum(2^(n-2*m)*(-1)^((n-m)/2) *sum(2^l*l!*binomial(m, l)*sum((k!*stirling1(l+k, l)*stirling2(n-2*m+l, k))/((l+k)!*(n-2*m+l)!), k, 0, n-2*m+l), l, 0, m)*bern(m)/(m)!, m, 1, n);
CROSSREFS
KEYWORD
sign
AUTHOR
Vladimir Kruchinin, Nov 07 2011
STATUS
approved