OFFSET
0,2
MAPLE
-sqrt(exp(LambertW(-x)))*(LambertW(-x) + 1): series(%, x, 32):
seq(2^n*n!*coeff(%, x, n), n=0..17);
MATHEMATICA
a[n_] := 2^n n! SeriesCoefficient[-Sqrt[Exp[ProductLog[-x]]] (ProductLog[ -x ] + 1), {x, 0, n}]; Table[a[n], {n, 0, 17}] (* Jean-François Alcover, Jul 21 2019 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Peter Luschny, Dec 07 2018
STATUS
approved