OFFSET
0,3
EXAMPLE
G.f.: A(x) = 1 + x + 2*x^2 + 7*x^3 + 37*x^4 + 279*x^5 + 2919*x^6 +...
where:
A(x) = 1 + x*A(x) + x^2*A(2*x)^2 + x^3*A(3*x)^3 + x^4*A(4*x)^4 + x^5*A(5*x)^5 +...
PROG
(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(k=1, n, A=1+sum(j=1, n, x^j*subst(A, x, j*x)^j)); polcoeff(A, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Sep 08 2011
STATUS
approved