OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..30
FORMULA
a(n) = [x^n] (n!)^n * (Sum_{j=0..n} x^j/(j!)^n)^n.
a(n) = A245397(n,n).
MAPLE
b:= proc(n, i, k) option remember; `if`(n=0 or i=1, 1,
add(b(n-j, i-1, k)*binomial(n, j)^k, j=0..n))
end:
a:= n-> b(n$3):
seq(a(n), n=0..12);
MATHEMATICA
b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i < 1, 0,
Sum[b[n-j, i-1, k]*Binomial[n, j]^(k-1)/j!, {j, 0, n}]]];
a[n_] := n!*b[n, n, n];
Table[a[n], {n, 0, 12}] (* Jean-François Alcover, Jun 27 2022, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 21 2014
STATUS
approved