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A054648
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Number of labeled pure 2-complexes on n nodes (0-simplexes) with 4 2-simplexes and 11 1-simplexes.
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0
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360, 13230, 137760, 835380, 3679200, 13056120, 39584160, 106383420, 259819560, 586936350, 1242521280, 2489618040, 4758324480, 8728907040, 15446635200, 26477304840, 44114190120, 71649152190, 113722852320, 176771479500
(list; graph; refs; listen; history; internal format)
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OFFSET
| 6,1
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COMMENTS
| 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.
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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.
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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.
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CROSSREFS
| Cf. A054557-A054562.
Sequence in context: A056322 A056313 A192829 * A166785 A200210 A145412
Adjacent sequences: A054645 A054646 A054647 * A054649 A054650 A054651
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KEYWORD
| nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 16 2000
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EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), Apr 16 2000
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