A346432 - OEIS

A346432

a(0) = 1; a(n) = n! * Sum_{k=0..n-1} (n-k+1) * a(k) / k!.

1, 2, 14, 144, 1968, 33600, 688320, 16450560, 449326080, 13806858240, 471395635200, 17703899136000, 725338710835200, 32193996432998400, 1538840509503897600, 78808952068374528000, 4305129487814098944000, 249876735246162984960000, 15356385691181506363392000

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..18.

FORMULA

E.g.f.: 1 / (2 - 1 / (1 - x)^2).

E.g.f.: 1 / (1 - Sum_{k>=1} (k+1) * x^k).

a(0) = 1, a(1) = 2, a(2) = 14; a(n) = 4 * n * a(n-1) - 2 * n * (n-1) * a(n-2).

a(n) = Sum_{k=0..n} (-1)^(n-k) * Stirling1(n,k) * 2^k * A000670(k).

a(n) = n! * A003480(n).

MATHEMATICA