|
| |
|
|
A052739
|
|
A simple context-free grammar in a labeled universe.
|
|
0
| |
|
|
0, 0, 2, 24, 288, 4800, 103680, 2741760, 85800960, 3100446720, 127037030400, 5819550105600, 294727768473600, 16350861400473600, 986127353590579200, 64238655955009536000, 4495021381191204864000, 336249161369543245824000
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,3
|
|
|
LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 695
|
|
|
FORMULA
| E.g.f.: 1/2-1/2*(1-4*x-4*x^2)^(1/2)-x^2-x
Recurrence: {a(1)=0, a(2)=2, a(3)=24, a(4)=288, (-4*n^2+4)*a(n)+(-4*n-2)*a(n+1)+a(n+2)}
|
|
|
MAPLE
| spec := [S, {B=Prod(Z, Z), S=Prod(C, C), C=Union(B, S, Z)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
|
CROSSREFS
| Sequence in context: A061190 A002006 A065101 * A135389 A065513 A119491
Adjacent sequences: A052736 A052737 A052738 * A052740 A052741 A052742
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
| |
|
|
