0,2

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

Laguerre transform of double factorials 2^n*n!=A000165(n). [From Paul Barry (pbarry(AT)wit.ie), Aug 08 2008]

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.

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

E.g.f.: 1/(1-3*x).

a(n)=sum{k=0..n, binomial(n,k)(n!/k!)2^k*k!}. [From Paul Barry (pbarry(AT)wit.ie), Aug 08 2008]

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

restart: G(x):=(1-3*x)^(n-2): f[0]:=G(x): for n from 1 to 29 do f[n]:=diff(f[n-1], x) od:x:=0:seq(f[n], n=0..16); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 04 2009]

Table[3^n*Gamma[1 + n], {n, 0, 20}] - Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Oct 30 2008

s=3; lst={1, s}; Do[s+=n*s+s; AppendTo[lst, s], {n, 4, 5!, 3}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 08 2008]

Cf. A000142, A007559, A008544, A051141, A000165.

Adjacent sequences: A032028 A032029 A032030 this_sequence A032032 A032033 A032034

Sequence in context: A052182 A115415 A065058 this_sequence A127646 A089466 A107403

nonn,easy,nice

Christian G. Bower (bowerc(AT)usa.net)