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Search: id:A054563
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| A054563 |
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n*(n^2 - 1)*(n + 2)*(n^2 + 4*n + 6)/72. |
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+0
3
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| 0, 0, 6, 45, 190, 595, 1540, 3486, 7140, 13530, 24090, 40755, 66066, 103285, 156520, 230860, 332520, 468996, 649230, 883785, 1185030, 1567335, 2047276, 2643850, 3378700, 4276350, 5364450, 6674031, 8239770, 10100265, 12298320, 14881240
(list; graph; listen)
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OFFSET
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2,3
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COMMENT
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Number of labeled pure 2-complexes on n nodes with 2 2-simplexes.
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REFERENCES
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L. Berzolari, Allgemeine Theorie der Ho"heren Ebenen Algebraischen Kurven, Encyclopa"die der Mathematischen Wissenschaften mit Einschluss ihrer Anwendungen. Band III_2. Heft 3, Leipzig: B.G. Teubner, 1906. p. 353.
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FORMULA
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C(C(n, 3), 2) = 6*C(n, 4)+15*C(n, 5)+10*C(n, 6) = n*(n-1)*(n-2)*(n-3)*(n^2+2)/72.
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CROSSREFS
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Sequence in context: A131513 A123141 A122096 this_sequence A003486 A024077 A097129
Adjacent sequences: A054560 A054561 A054562 this_sequence A054564 A054565 A054566
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KEYWORD
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easy,nonn,nice
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 10 2000
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Apr 11 2000
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