|
Search: id:A054648
|
|
|
| A054648 |
|
Number of labeled pure 2-complexes on n nodes (0-simplexes) with 4 2-simplexes and 11 1-simplexes. |
|
+0
1
|
|
| 360, 13230, 137760, 835380, 3679200, 13056120, 39584160, 106383420, 259819560, 586936350, 1242521280, 2489618040, 4758324480, 8728907040, 15446635200, 26477304840, 44114190120, 71649152190, 113722852320, 176771479500
(list; graph; listen)
|
|
|
OFFSET
|
6,1
|
|
|
COMMENT
|
Number of {T_1,T_2,...,T_k} where T_i,i=1..k are 3-subsets of an n-set such that {D | D is 2-subset of T_i for some i=1..k} has l elements; k=4,l=11.
|
|
REFERENCES
|
V. Jovovic, On the number of two-dimensional simplicial complexes (in Russian), Metody i sistemy tekhnicheskoy diagnostiki, Vypusk 16, Mezhvuzovskiy zbornik nauchnykh trudov, Izdatelstvo Saratovskogo universiteta, 1991.
|
|
FORMULA
|
a(n)=360*C(n, 6)+10710*C(n, 7)+42000*C(n, 8)+41580*C(n, 9)+12600*C(n, 10)=n*(n-1)*(n-2)*(n-3)*(n-4)*(n-5)*(n^4+3*n^3-58*n^2-120*n+1008)/288.
|
|
CROSSREFS
|
Cf. A054557-A054562.
Sequence in context: A033592 A056322 A056313 this_sequence A166785 A145412 A156032
Adjacent sequences: A054645 A054646 A054647 this_sequence A054649 A054650 A054651
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 16 2000
|
|
EXTENSIONS
|
More terms from James A. Sellers (sellersj(AT)math.psu.edu), Apr 16 2000
|
|
|
Search completed in 0.002 seconds
|
