OFFSET
1,4
FORMULA
a(n) = (2*n-1)!/(n-1)! - n! - Sum_{i=2..n} binomial(n-1, n-i)*n*n!.
PROG
(PARI) a(n)=(2*n-1)!/(n-1)!-n!-sum(i=2, n, binomial(n-1, n-i)*n*n!)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jon Perry, Jul 27 2003
STATUS
approved