OFFSET
0,2
EXAMPLE
G.f.: A(x) = 1 + 2*x + 10*x^2 + 50*x^3 + 290*x^4 + 1766*x^5 +...,
where A(x) = 1/((1 - 2*x*A(x)) * (1 - 2*x^2*A(x^2)) * (1 - 2*x^3*A(x^3)) * ...).
PROG
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=1/prod(k=1, n, (1-2*x^k*subst(A, x, x^k+x*O(x^n))))); polcoeff(A, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jan 31 2012
STATUS
approved