|
Search: id:A052678
|
|
|
| A052678 |
|
A simple regular expression in a labeled universe. |
|
+0
1
|
|
| 0, 0, 0, 6, 72, 1080, 19440, 408240, 9797760, 264539520, 7936185600, 261894124800, 9428188492800, 367699351219200, 15443372751206400, 694951773804288000, 33357685142605824000, 1701241942272897024000
(list; graph; listen)
|
|
|
OFFSET
|
0,4
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 626
|
|
FORMULA
|
E.g.f.: -x^3/(-1+3*x)
Recurrence: {a(1)=0, a(0)=0, a(2)=0, a(3)=6, (-3*n-3)*a(n)+a(n+1)}
1/27*3^n*n!
|
|
MAPLE
|
spec := [S, {S=Prod(Z, Z, Z, Sequence(Union(Z, Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Adjacent sequences: A052675 A052676 A052677 this_sequence A052679 A052680 A052681
Sequence in context: A007031 A067419 A113331 this_sequence A052719 A063965 A047058
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
|
Search completed in 0.003 seconds
|
