A264153 a(n) = ((2*n)!)^2 / 2^n.

1, 2, 144, 64800, 101606400, 411505920000, 3585039575040000, 59375425441812480000, 1710012252724199424000000, 80059353648041568632832000000, 5780285333388601255290470400000000, 616883611349898303167109582028800000000, 93983451956379706284115479041251737600000000

Offset: 0

Author

Peter Luschny, Nov 06 2015

Keywords

• nonn

Crossrefs

Cf. A000079, A000680, A134372, A264152.

Programs

Maple

a := n -> (2*n)!^2/2^n; seq(a(n), n=0..10);

Sage

a = lambda n: factorial(2*n)^2 >> n
[a(n) for n in range(11)]

Formula

a(n) = A134372(n)/A000079(n).

a(n)*A264152(n) = A134372(n)*A006882(2*n-1)/A006882(n).

a(n)/A264152(n) is an integer: 1, 1, 24, 1620,....