OFFSET
9,2
FORMULA
E.g.f. (1/sqrt(1-x^2))*((x/(1-x))^9)/9!.
a(n)=(n!/9!)*sum(binomial(2*k, k)*binomial(n-2*k-1, 8)/(4^k), k=0..floor((n-9)/2)), n>=9.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Aug 23 2005
STATUS
approved