|
Search: id:A052586
|
|
|
| A052586 |
|
A simple regular expression in a labeled universe. |
|
+0
1
|
|
| 1, 1, 2, 6, 48, 360, 2880, 30240, 362880, 4717440, 68947200, 1117670400, 19639065600, 373621248000, 7671689625600, 168689993472000, 3954407288832000, 98525417582592000, 2599363724525568000
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 531
|
|
FORMULA
|
E.g.f.: (-1+x^3)/(-1+x+x^3)
Recurrence: {a(1)=1, a(0)=1, a(3)=6, a(2)=2, (-11*n-6-n^3-6*n^2)*a(n)+(-n-3)*a(n+2)+a(n+3)}
Sum(1/31*(-2*_alpha+9*_alpha^2+6)*_alpha^(-1-n), _alpha=RootOf(-1+_Z+_Z^3))*n!
|
|
MAPLE
|
spec := [S, {S=Sequence(Prod(Z, Sequence(Prod(Z, Z, Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Sequence in context: A052657 A092143 A052593 this_sequence A052554 A052743 A052587
Adjacent sequences: A052583 A052584 A052585 this_sequence A052587 A052588 A052589
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
|
Search completed in 0.002 seconds
|
