[go: up one dir, main page]

login
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
OFFSET
0,4
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
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
STATUS
approved