OFFSET
0,2
COMMENTS
For n >= 1 a(n) is the order of the wreath product of the symmetric group S_n and the Abelian group (C_10)^n. - Ahmed Fares (ahmedfares(AT)my-deja.com), May 07 2001
LINKS
FORMULA
a(n) = 10*A035279(n) = Product_{k=1..n} 10*k, n >= 1; a(0) := 1.
a(n) = n!*10^n =: (10*n)(!^10);
E.g.f.: 1/(1-10*x).
G.f.: 1/(1 - 10*x/(1 - 10*x/(1 - 20*x/(1 - 20*x/(1 - 30*x/(1 - 30*x/(1 - ...))))))), a continued fraction. - Ilya Gutkovskiy, May 12 2017
From Amiram Eldar, Jun 25 2020: (Start)
Sum_{n>=0} 1/a(n) = e^(1/10).
Sum_{n>=0} (-1)^n/a(n) = e^(-1/10). (End)
MAPLE
with(combstruct):A:=[N, {N=Cycle(Union(Z$10))}, labeled]: seq(count(A, size=n)/10, n=0..14); # Zerinvary Lajos, Dec 05 2007
MATHEMATICA
Array[#!*10^# &, 14, 0] (* Michael De Vlieger, Sep 04 2017 *)
PROG
(Magma) [10^n*Factorial(n): n in [0..20]]; // Vincenzo Librandi, Oct 05 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
STATUS
approved