|
Search: id:A052639
|
|
|
| A052639 |
|
A simple regular expression in a labeled universe. |
|
+0
1
|
|
| 1, 0, 0, 6, 48, 480, 6480, 100800, 1774080, 35199360, 776563200, 18840729600, 498640665600, 14297239756800, 441470866636800, 14605415016192000, 515412006100992000, 19325209343311872000, 767215648278503424000
(list; graph; listen)
|
|
|
OFFSET
|
0,4
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 585
|
|
FORMULA
|
E.g.f.: (-1+2*x)/(-1+2*x+x^3)
Recurrence: {a(1)=0, a(0)=1, a(2)=0, (-11*n-6-n^3-6*n^2)*a(n)+(-2*n-6)*a(n+2)+a(n+3)}
Sum(-1/59*(8+6*_alpha^2-25*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+2*_Z+_Z^3))*n!
|
|
MAPLE
|
spec := [S, {S=Sequence(Prod(Z, Z, Z, Sequence(Union(Z, Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Sequence in context: A085457 A105627 A051578 this_sequence A053506 A055861 A052567
Adjacent sequences: A052636 A052637 A052638 this_sequence A052640 A052641 A052642
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
|
Search completed in 0.002 seconds
|
