|
Search: id:A052867
|
|
| |
|
| 0, 0, 2, 12, 84, 720, 7440, 90720, 1280160, 20563200, 370863360, 7424524800, 163419379200, 3923023104000, 102011054745600, 2856483889459200, 85697132032512000, 2742350070620160000, 93240613775941632000
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 838
|
|
FORMULA
|
E.g.f.: ln(-(-1+x)^2/(-1+2*x))
Recurrence: {a(1)=0, a(2)=2, (2*n^2+2*n)*a(n)-3*(n+1)*a(n+1)+a(n+2)}
-2*GAMMA(n+1)+2^(n+1)*GAMMA(n+1)
|
|
MAPLE
|
spec := [S, {B=Sequence(Z, 1 <= card), C=Prod(B, B), S= Cycle(C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Sequence in context: A006657 A105927 A052887 this_sequence A097237 A055531 A059435
Adjacent sequences: A052864 A052865 A052866 this_sequence A052868 A052869 A052870
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
|
Search completed in 0.002 seconds
|
