A372993 a(n) = n! a(n-1) / a(n-2), where a(0) = 1, a(1) = 1.

1, 1, 2, 12, 144, 1440, 7200, 25200, 141120, 2032128, 52254720, 1026432000, 9408960000, 57081024000, 528881633280, 12116197416960, 479322095616000, 14071151001600000, 187950374092800000, 1624830984032256000, 21032437860687052800, 661340826849411072000

Offset

0,3

Links

Table of n, a(n) for n=0..21.

Mathematica

a[0] = 1; a[1] = 1;
a[n_] := a[n] = n! a[n - 1]/a[n - 2];
Table[a[n], {n, 0, 22}]

Crossrefs

Cf. A000142, A372994.

Sequence in context: A009747 A208866 A334174 * A067601 A365284 A052740

Adjacent sequences: A372990 A372991 A372992 * A372994 A372995 A372996

Keyword

nonn

Author

Clark Kimberling, Jul 16 2024

Status

approved