A010794 a(n) = n!*(n+5)!/5!.

1, 6, 84, 2016, 72576, 3628800, 239500800, 20118067200, 2092278988800, 263627152588800, 39544072888320000, 6959756828344320000, 1419790392982241280000, 332230951957844459520000, 88373433220786626232320000, 26512029966235987869696000000

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200
• Index entries for sequences related to factorial numbers.

Crossrefs

Cf. A010791, A010792, A010793, A010795.

Programs

Magma

[Factorial(n)*Factorial(n+5) / Factorial(5): n in [0..20]]; // Vincenzo Librandi, Oct 04 2011

Maple

f := n->n!*(n+5)!/5!;

Mathematica

With[{c=5!},Table[(n!(n+5)!)/c,{n,0,20}]] (* Harvey P. Dale, Oct 03 2011 *)

PARI

a(n)=n!^2*binomial(n+5,5) \\ Charles R Greathouse IV, Oct 23 2023

Formula

From Amiram Eldar, Sep 27 2022: (Start)

Sum_{n>=0} 1/a(n) = 120*BesselI(5,2).

Sum_{n>=0} (-1)^n/a(n) = 120*BesselJ(5,2). (End)

a(n) = 1/([x^n] hypergeom([], [6], x)). - Peter Luschny, Sep 13 2024

Extensions

More terms from Harvey P. Dale, Oct 03 2011