OFFSET
0,3
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..50
PROG
(PARI) \\ See A340022 for permcount, edges.
InvEulerT(v)={my(p=log(1+x*Ser(v))); dirdiv(vector(#v, n, polcoef(p, n)), vector(#v, n, 1/n))}
seq(n) = {concat([1], InvEulerT(Vec(sum(k=1, n, my(s=0); forpart(p=k, s+=permcount(p) * 2^edges(p) * x^k/prod(j=1, #p, 1 - x^p[j] + O(x^(n-k+1)))); s/k!))))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Jan 01 2021
STATUS
approved