|
| |
|
|
A052753
|
|
A simple grammar.
|
|
1
| |
|
|
0, 0, 0, 0, 24, 240, 2040, 17640, 162456, 1614816, 17368320, 201828000, 2526193824, 33936357312, 487530074304, 7463742249600, 121367896891776, 2089865973021696, 37999535417459712, 727710096185266176
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,5
|
|
|
LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 709
|
|
|
FORMULA
| E.g.f.: ln(-1/(-1+x))^4
Recurrence: {a(1)=0, a(0)=0, a(2)=0, (1+4*n+6*n^2+4*n^3+n^4)*a(n+1)+(-4*n^3-15-18*n^2-28*n)*a(n+2)+(6*n^2+24*n+25)*a(n+3)+(-4*n-10)*a(n+4)+a(n+5), a(3)=0, a(4)=24}
|
|
|
MAPLE
| spec := [S, {B=Cycle(Z), S=Prod(B, B, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
|
CROSSREFS
| Sequence in context: A056269 A000919 A014340 * A052520 A052724 A000536
Adjacent sequences: A052750 A052751 A052752 * A052754 A052755 A052756
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
| |
|
|
