A262032 - OEIS

%I #11 Sep 08 2022 08:46:13

%S 1,2,12,6720,871782912000,2192756974447446084726816768000000,

%T 176231850258172450143657485187724278892868772464646100276113742187798200320000000000000

%N a(n) = (2^n)! / n!.

%F a(n) = A000722(n) / A000142(n).

%e For n = 2, a(n) = (2^n)! / n! = (2^2)! / 2! = 12.

%t Table[(2^n)!/n!, {n, 0, 6}] (* _Michael De Vlieger_, Sep 09 2015 *)

%o (PARI) a(n) = (2^n)! / n!;

%o vector(10, n, a(n-1))

%o (Magma) [Factorial(2^n) / Factorial(n): n in [0..7]]; // _Vincenzo Librandi_, Sep 10 2015

%Y Cf. A000722, A000142.

%K nonn,easy

%O 0,2

%A _Altug Alkan_, Sep 08 2015