|
| |
|
|
A052599
|
|
E.g.f. 1/(1-2x-x^3).
|
|
0
| |
|
|
1, 2, 8, 54, 480, 5280, 69840, 1078560, 19031040, 377758080, 8331724800, 202138675200, 5349968870400, 153396430387200, 4736570917478400, 156702542540544000, 5529893367398400000, 207341583834857472000
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,2
|
|
|
LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 544
|
|
|
FORMULA
| E.g.f.: -1/(-1+2*x+x^3)
Recurrence: {a(0)=1, a(1)=2, a(2)=8, (-11*n-6-n^3-6*n^2)*a(n) +(-2*n-6)*a(n+2) +a(n+3)=0}
Sum(1/59*(16+12*_alpha^2+9*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+2*_Z+_Z^3))*n!
a(n) = n!*A008998(n). - R. J. Mathar, Nov 27 2011
|
|
|
MAPLE
| spec := [S, {S=Sequence(Union(Z, Z, Prod(Z, Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
|
CROSSREFS
| Sequence in context: A079503 A052694 A069729 * A052662 A073564 A199576
Adjacent sequences: A052596 A052597 A052598 * A052600 A052601 A052602
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
| |
|
|
