OFFSET
0,3
FORMULA
a(n) = 1 - Sum_{j=0..n-1} a(j) * (-1)^(n-j) * C(j^2 + n-j-1, n-j) for n>0, with a(0)=1.
EXAMPLE
1/(1-x) = 1 + x/(1+x) + 2*x^2/(1+x)^4 + 8*x^3/(1+x)^9 + 54*x^4/(1+x)^16 +...
PROG
(PARI) {a(n)=if(n==0, 1, polcoeff(-(1-x)*sum(m=0, n-1, a(m)*x^m/(1+x +x*O(x^n))^(m^2)), n))}
(PARI) {a(n)=if(n==0, 1, 1 - sum(j=0, n-1, a(j)*(-1)^(n-j)*binomial(j^2+n-j-1, n-j)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 24 2010
STATUS
approved