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Search: id:A054647
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| A054647 |
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Number of labeled pure 2-complexes on n nodes (0-simplexes) with 4 2-simplexes and 12 1-simplexes. |
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1
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| 30, 2310, 42840, 391545, 2375100, 10980585, 41761720, 136963255, 399689290, 1060984925, 2603641040, 5979294230, 12973080120, 26794003110, 53000811600, 100914240770, 185718969590, 331524753560, 575738427880, 975199600375
(list; graph; listen)
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OFFSET
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6,1
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COMMENT
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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=12.
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REFERENCES
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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
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a(n)=30*C(n, 6)+2100*C(n, 7)+25200*C(n, 8)+86625*C(n, 9)+116550*C(n, 10)+69300*C(n, 11)+15400*C(n, 12)=n*(n-1)*(n-2)*(n-3)*(n-4)*(n-5)*(n^6+3*n^5-86*n^4-240*n^3+2704*n^2+5232*n-34128)/31104.
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CROSSREFS
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Cf. A054557-A054562.
Sequence in context: A092617 A056093 A056070 this_sequence A061162 A138916 A091544
Adjacent sequences: A054644 A054645 A054646 this_sequence A054648 A054649 A054650
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KEYWORD
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nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 16 2000
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Apr 16 2000
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