OFFSET
0,2
PROG
(PARI) {a(n)=local(A=1+x+x*O(x^n), B); for(n=0, n, B=serreverse(x/A^3); A=1/(1-B)^2); polcoeff(A, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Oct 03 2008
STATUS
approved