OFFSET
0,3
EXAMPLE
G.f.: A(x) = 1 + x + 2*x^2 + 12*x^3 + 41*x^4 + 134*x^5 +...
log(A(x)) = x*(1+x) + x^2*(1 + 20*x + x^2)/2 + x^3*(1 + 84*x + 84*x^2 + x^3)/3 + x^4*(1 + 220*x + 924*x^2 + 220*x^3 + x^4)/4 +...
PROG
(PARI) {a(n)=polcoeff( exp(sum(m=1, n, sum(k=0, m, binomial(3*m, 3*k)*x^k) *x^m/m) +x*O(x^n)), n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Mar 19 2011
STATUS
approved