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A052745 A simple grammar. 1
0, 0, 0, 6, 24, 110, 600, 3836, 28224, 235224, 2191680, 22584672, 255087360, 3134139840, 41620400640, 594082771200, 9070900715520, 147531542054400, 2546434166169600, 46489412442009600, 895079522340864000, 18125736166340812800, 385129713617510400000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..22.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 701

FORMULA

E.g.f.: log(-1/(-1+x))^2*x.

Recurrence: a(1)=0, a(2)=0, a(3)=6, (-n+n^4+n^3-3*n^2+2)*a(n)+(-2*n^3-3*n^2+2*n)*a(n+1)+(n^2+n)*a(n+2)=0.

a(n) = (-1)^(n+1)*2*n*Stirling1(n-1, 2). - Vladeta Jovovic, Nov 08 2003

MAPLE

spec := [S, {B=Cycle(Z), S=Prod(Z, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);

MATHEMATICA

Range[0, 30]! CoefficientList[Series[Log[-1/(-1 + x)]^2 x, {x, 0, 30}], x] (* Vincenzo Librandi, Jul 08 2015 *)

PROG

(Maxima) makelist((-1)^(n+1)*2*n*stirling1(n-1, 2), n, 0, 20); /* Bruno Berselli, May 25 2011 */

(MAGMA) [0] cat [(-1)^(n+1)*2*n*StirlingFirst(n-1, 2): n in [1..30]]; // Vincenzo Librandi, Jul 08 2015

CROSSREFS

Sequence in context: A075484 A122739 A038380 * A187668 A273813 A293257

Adjacent sequences:  A052742 A052743 A052744 * A052746 A052747 A052748

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

STATUS

approved

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Last modified July 28 04:08 EDT 2021. Contains 346316 sequences. (Running on oeis4.)