A100734 a(n) = (5*n)!.

1, 120, 3628800, 1307674368000, 2432902008176640000, 15511210043330985984000000, 265252859812191058636308480000000, 10333147966386144929666651337523200000000

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..90

Formula

E.g.f.: 1/(1-x^5).

From Ilya Gutkovskiy, Jan 20 2017: (Start)

a(n) ~ sqrt(2*Pi)*5^(5*n + 1/2)*n^(5*n + 1/2)/exp(5*n).

Sum_{n>=0} 1/a(n) = A269296. (End)

Mathematica

(5*Range[0, 10])! (* Harvey P. Dale, May 06 2015 *)

Prog

(Magma) [Factorial(5*n): n in [0..10]]; // Vincenzo Librandi, Sep 24 2011

Crossrefs

Cf. A000142, A010050, A100732, A100733, A268506, A269296.

Sequence in context: A308327 A172897 A258925 * A115463 A003922 A210279

Adjacent sequences: A100731 A100732 A100733 * A100735 A100736 A100737

Keyword

nonn,easy

Author

Ralf Stephan, Dec 08 2004

Status

approved