|
Search: id:A052613
|
|
|
| A052613 |
|
A simple regular expression in a labeled universe. |
|
+0
1
|
|
| 1, 0, 2, 6, 72, 720, 10080, 156240, 2822400, 56972160, 1280966400, 31654022400, 853580851200, 24932991283200, 784343085926400, 26435945023488000, 950417730662400000, 36304660098330624000, 1468365202287599616000
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 558
|
|
FORMULA
|
E.g.f.: -(-1+2*x)/(x^3-x^2-2*x+1)
Recurrence: {a(1)=0, a(0)=1, a(2)=2, (n^3+6*n^2+11*n+6)*a(n)+(-n^2-5*n-6)*a(n+1)+(-2*n-6)*a(n+2)+a(n+3)}
Sum(1/7*(-1+3*_alpha)*_alpha^(-1-n), _alpha=RootOf(_Z^3-_Z^2-2*_Z+1))*n!
|
|
MAPLE
|
spec := [S, {S=Sequence(Prod(Z, Z, Sequence(Prod(Z, Sequence(Z)))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Sequence in context: A000896 A103527 A152885 this_sequence A156493 A117515 A085865
Adjacent sequences: A052610 A052611 A052612 this_sequence A052614 A052615 A052616
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
|
Search completed in 0.002 seconds
|
