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%I #4 Jul 19 2024 19:15:54
%S 1,1,2,12,144,1440,7200,25200,141120,2032128,52254720,1026432000,
%T 9408960000,57081024000,528881633280,12116197416960,479322095616000,
%U 14071151001600000,187950374092800000,1624830984032256000,21032437860687052800,661340826849411072000
%N a(n) = n! a(n-1) / a(n-2), where a(0) = 1, a(1) = 1.
%t a[0] = 1; a[1] = 1;
%t a[n_] := a[n] = n! a[n - 1]/a[n - 2];
%t Table[a[n], {n, 0, 22}]
%Y Cf. A000142, A372994.
%K nonn
%O 0,3
%A _Clark Kimberling_, Jul 16 2024