|
Search: id:A032031
|
|
|
| A032031 |
|
Triple factorial numbers: (3n)!!!=3^n*n!. |
|
+0
19
|
|
| 1, 3, 18, 162, 1944, 29160, 524880, 11022480, 264539520, 7142567040, 214277011200, 7071141369600, 254561089305600, 9927882482918400, 416971064282572800, 18763697892715776000, 900657498850357248000
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
For n >= 1 a(n) is the order of the wreath product of the symmetric group S_n and the elementary abelian group (C_3)^n. - Ahmed Fares (ahmedfares(AT)my-deja.com), May 07 2001
|
|
REFERENCES
|
Michael Z. Spivey and Laura L. Steil, The k-Binomial Transforms and the Hankel Transform, Journal of Integer Sequences, Vol. 9 (2006), Article 06.1.1.
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 491
Alexsandar Petojevic, The Function vM_m(s; a; z) and Some Well-Known Sequences, Journal of Integer Sequences, Vol. 5 (2002), Article 02.1.7
|
|
FORMULA
|
E.g.f.: 1/(1-3*x).
|
|
MAPLE
|
with(combstruct):ZL:=[T, {T=Union(Z, Prod(Epsilon, Z, T), Prod(T, Z, Epsilon), Prod(T, Z))}, labeled]:seq(count(ZL, size=i)/i, i=1..17); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 16 2007
|
|
CROSSREFS
|
Cf. A000142, A007559, A008544, A051141, A000165.
Sequence in context: A052182 A115415 A065058 this_sequence A127646 A089466 A107403
Adjacent sequences: A032028 A032029 A032030 this_sequence A032032 A032033 A032034
|
|
KEYWORD
|
nonn,easy,nice
|
|
AUTHOR
|
Christian G. Bower (bowerc(AT)usa.net)
|
|
|
Search completed in 0.002 seconds
|
