OFFSET
0,2
EXAMPLE
G.f.: A(x) = 1 + 2*x + 9*x^2 + 90*x^3 + 2577*x^4 + 248236*x^5 +...;
A(x) = Sum_{n>=0} log(1 + 2^n*x + 3^n*x^2 + 4^n*x^3 +...)^n / n! ; surprisingly, this sum yields a series in x with integer coefficients.
PROG
(PARI) {a(n)=polcoeff(sum(i=0, n, log(sum(k=0, n, (k+1)^i*x^k)+x*O(x^n))^i/i!), n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jan 05 2008
STATUS
approved