OFFSET
0,3
FORMULA
a(n) = [x^n] Sum_{k>=0} x^k/(1 + n*k*x)^(k+1).
a(n) = Sum_{k=0..n} binomial(n,k)*(-n*k)^(n-k).
MATHEMATICA
Table[n! SeriesCoefficient[Exp[x Exp[-n x]], {x, 0, n}], {n, 0, 18}]
Table[SeriesCoefficient[Sum[x^k/(1 + n k x)^(k + 1), {k, 0, n}], {x, 0, n}], {n, 0, 18}]
Join[{1}, Table[Sum[Binomial[n, k] (-n k)^(n - k), {k, 0, n}], {n, 18}]]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Oct 08 2018
STATUS
approved