|
Search: id:A054559
|
|
|
| A054559 |
|
Number of labeled pure 2-complexes on n nodes (0-simplexes) with 5 2-simplexes and 8 1-simplexes. |
|
+0
2
|
|
| 30, 180, 630, 1680, 3780, 7560, 13860, 23760, 38610, 60060, 90090, 131040, 185640, 257040, 348840, 465120, 610470, 790020, 1009470, 1275120, 1593900, 1973400, 2421900, 2948400, 3562650, 4275180
(list; graph; listen)
|
|
|
OFFSET
|
5,1
|
|
|
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=5,l=8.
|
|
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)=30*C(n, 5)=n*(n-1)*(n-2)*(n-3)*(n-4)/4.
|
|
CROSSREFS
|
Cf. A054557.
Cf. A000389, A052787.
Adjacent sequences: A054556 A054557 A054558 this_sequence A054560 A054561 A054562
Sequence in context: A100430 A068236 A101098 this_sequence A042756 A042758 A071311
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 10 2000
|
|
|
Search completed in 0.002 seconds
|
