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A049308 Sextuple factorial numbers: product_{k=0..n-1} (6*k+4). 10
1, 4, 40, 640, 14080, 394240, 13404160, 536166400, 24663654400, 1282510028800, 74385581670400, 4760677226905600, 333247405883392000, 25326802847137792000, 2076797833465298944000, 182758209344946307072000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..15.

FORMULA

E.g.f.: (1-6*x)^(-2/3).

a(n) = 2^n*A008544(n).

G.f.: 1/(1-4x/(1-6x/(1-10x/(1-12x/(1-16x/(1-18x/(1-22x/(1-24x/(1-28x/(1-... (continued fraction). - Philippe Deléham, Jan 08 2012

a(n) = (-2)^n*sum_{k=0..n} 3^k*s(n+1,n+1-k), where s(n,k) are the Stirling numbers of the first kind, A048994. - Mircea Merca, May 03 2012

G.f.: ( 1 - 1/Q(0) )/x/2 where Q(k) =1 - x*(6*k-2)/(1 - x*(6*k+6)/Q(k+1) ); (continued fraction). - Sergei N. Gladkovskii, Mar 20 2013

MATHEMATICA

s=1; lst={s}; Do[s+=n*s; AppendTo[lst, s], {n, 3, 5!, 6}]; lst (* Vladimir Joseph Stephan Orlovsky, Nov 08 2008 *)

CROSSREFS

Cf. A008544, A011781, A008543.

Sequence in context: A141010 A141011 A090359 * A227055 A205671 A234294

Adjacent sequences:  A049305 A049306 A049307 * A049309 A049310 A049311

KEYWORD

nonn,easy

AUTHOR

Joe Keane (jgk(AT)jgk.org)

STATUS

approved

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Last modified November 18 04:44 EST 2019. Contains 329248 sequences. (Running on oeis4.)