OFFSET
0,3
FORMULA
G.f. satisfies: A(x) = G(x*A(x)) where G(x) = A(x/G(x)) is the g.f. of A198950.
EXAMPLE
G.f.: A(x) = 1 + x + 3*x^2 + 12*x^3 + 51*x^4 + 233*x^5 + 1126*x^6 +...
where
log(A(x)) = (1 + x)*x*A(x) + (1 + 2^3*x + x^2)*x^2*A(x)^2/2 +
(1 + 3^3*x + 3^3*x^2 + x^3)*x^3*A(x)^3/3 +
(1 + 4^3*x + 6^3*x^2 + 4^3*x^3 + x^4)*x^4*A(x)^4/4 +
(1 + 5^3*x + 10^3*x^2 + 10^3*x^3 + 5^3*x^4 + x^5)*x^5*A(x)^5/5 +...
more explicitly,
log(A(x)) = x + 5*x^2/2 + 28*x^3/3 + 149*x^4/4 + 821*x^5/5 + 4664*x^6/6 + 26839*x^7/7 +...
The g.f. satisfies A(x) = G(x*A(x)) where G(x) is the g.f. of A198950:
G(x) = 1 + x + 2*x^2 + 5*x^3 + 10*x^4 + 22*x^5 + 58*x^6 + 150*x^7 + 392*x^8 +...
PROG
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=exp(sum(m=1, n, sum(j=0, m, binomial(m, j)^3*x^j)*(x*A+x*O(x^n))^m/m))); polcoeff(A, n, x)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 11 2011
STATUS
approved