|
Search: id:A052656
|
|
|
| A052656 |
|
A simple regular expression in a labeled universe. |
|
+0
1
|
|
| 0, 1, 8, 24, 192, 1920, 23040, 322560, 5160960, 92897280, 1857945600, 40874803200, 980995276800, 25505877196800, 714164561510400, 21424936845312000, 685597979049984000, 23310331287699456000
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 603
|
|
FORMULA
|
E.g.f.: x*(-2*x+4*x^2-1)/(-1+2*x)
Recurrence: {a(1)=1, a(0)=0, (-2*n-2)*a(n)+a(n+1), a(2)=8, a(3)=24}
2^(n-1)*n!
|
|
MAPLE
|
spec := [S, {S=Prod(Z, Union(Z, Z, Sequence(Union(Z, Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Sequence in context: A098070 A100042 A061027 this_sequence A094061 A002268 A050893
Adjacent sequences: A052653 A052654 A052655 this_sequence A052657 A052658 A052659
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
|
Search completed in 0.002 seconds
|
