a(n) = (n!)^n * Sum_{k=1..n} (-1)^(k+1) / k^n.

A336250

a(n) = (n!)^n * Sum_{k=1..n} (-1)^(k+1) / k^n.

Terms

    a(0) =0a(1) =1a(2) =3a(3) =197a(4) =313840a(5) =24191662624

External references