|
Search: id:A052625
|
|
|
| A052625 |
|
A simple regular expression in a labeled universe. |
|
+0
1
|
|
| 1, 0, 0, 6, 48, 360, 3600, 45360, 645120, 10160640, 177811200, 3432844800, 72329241600, 1650160512000, 40537905408000, 1067062284288000, 29961435119616000, 893842506805248000, 28234468042260480000
(list; graph; listen)
|
|
|
OFFSET
|
0,4
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 571
|
|
FORMULA
|
E.g.f.: -(-1+x)^2/(-1+2*x-x^2+x^3)
Recurrence: {a(1)=0, a(0)=1, a(2)=0, (-11*n-6-n^3-6*n^2)*a(n)+(n^2+5*n+6)*a(n+1)+(-2*n-6)*a(n+2)+a(n+3)}
Sum(-1/23*(2-11*_alpha+6*_alpha^2)*_alpha^(-1-n), _alpha=RootOf(-1+2*_Z-_Z^2+_Z^3))*n!
|
|
MAPLE
|
spec := [S, {S=Sequence(Prod(Z, Z, Z, Sequence(Z), Sequence(Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Sequence in context: A049316 A024075 A052571 this_sequence A155130 A083233 A002918
Adjacent sequences: A052622 A052623 A052624 this_sequence A052626 A052627 A052628
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
|
Search completed in 0.002 seconds
|
