OFFSET
0,3
FORMULA
G.f.: A(x) = x/Series_Reversion(x*F(x)) where F(x) = g.f. of A133053.
EXAMPLE
PROG
(PARI) {a(n)=if(n==0, 1, polcoeff(x/serreverse(x*sum(m=0, n, polcoeff((1/x)*serreverse(x/(1+x+x^2+x^2*O(x^m))), m)^2 *x^m)+x^2*O(x^n)), n))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 01 2009
STATUS
approved