OFFSET
0,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..438
EXAMPLE
E.g.f.: A(x) = 1 + 3*x + 6*x^2/2! + 72*x^3/3! + 342*x^4/4! +...
A(x) = (1+3x)*(1+3x^2/2)^2*(1+3x^3/3)^3*(1+3x^4/4)^4*(1+3x^5/5)^5*...
MATHEMATICA
nmax = 20; CoefficientList[Series[Product[(1 + 3*x^k/k)^k, {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Oct 07 2020 *)
PROG
(PARI) {a(n, k=3)=n!*polcoeff(prod(m=1, n, (1+k*x^m/m+x*O(x^n))^m), n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 19 2010
STATUS
approved