|
| |
|
|
A052650
|
|
E.g.f. 1/((1-2x)(1-x)^2).
|
|
0
| |
|
|
1, 4, 22, 156, 1368, 14400, 177840, 2530080, 40844160, 738823680, 14816390400, 326439590400, 7840777190400, 203947385241600, 5711834461132800, 171375956623872000, 5484386299392000000, 186475536553033728000
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,2
|
|
|
LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 597
|
|
|
FORMULA
| E.g.f.: -1/(-1+2*x)/(-1+x)^2
Recurrence: {a(0)=1, a(1)=4, (2*n^2+8*n+6)*a(n)+(-3*n-7)*a(n+1)+a(n+2)=0}
(4*2^n-3-n)*n!
a(n) = n!*A000295(n+2). - R. J. Mathar, Nov 27 2011
|
|
|
MAPLE
| spec := [S, {S=Prod(Sequence(Z), Sequence(Z), Sequence(Union(Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
|
CROSSREFS
| Sequence in context: A049376 A083410 A052772 * A198053 A197925 A112697
Adjacent sequences: A052647 A052648 A052649 * A052651 A052652 A052653
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
| |
|
|
