OFFSET
0,4
EXAMPLE
G.f.: A(x) = 1 + x + x^2 + 2*x^3 + 5*x^4 + 17*x^5 + 129*x^6 + 823*x^7 +...
such that
A(x) = 1 + x*A(x)*A(-x) + x^2*A(2*x)*A(-2*x) + x^3*A(3*x)*A(-3*x) + x^4*A(4*x)*A(-4*x) + x^5*A(5*x)*A(-5*x) +...
where
A(x)*A(-x) = 1 + x^2 + 7*x^4 + 230*x^6 + 31667*x^8 + 17739221*x^10 + 40061321883*x^12 + 363330478847435*x^14 +...
PROG
(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=1, n, A=sum(k=0, n, x^k*subst(A, x, k*x +x*O(x^n))*subst(A, x, -k*x +x*O(x^n))) ); polcoeff(A, n)}
for(n=0, 30, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jan 27 2013
STATUS
approved