OFFSET
0,4
FORMULA
a(n)=(2*n-1)!*sum(k=1..n, ((-1)^(n-k)*sum(i=0..2*n, (2^i*stirling1(i+k,k)*binomial(2*n-k-1,i+k-1))/(i+k)!))), n>0, a(0)=1.
PROG
(Maxima)
a(n):=(2*n-1)!*sum(((-1)^(n-k)*sum((2^i*stirling1(i+k, k)*binomial(2*n-k-1, i+k-1))/(i+k)!, i, 0, 2*n)), k, 1, n);
CROSSREFS
KEYWORD
sign
AUTHOR
Vladimir Kruchinin, May 30 2011
STATUS
approved