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Search: id:A015251
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| A015251 |
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Gaussian binomial coefficient [ n,2 ] for q=-3. |
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+0
1
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| 1, 7, 70, 610, 5551, 49777, 448540, 4035220, 36321901, 326882347, 2941985410, 26477735830, 238300021051, 2144698993717, 19302294530680, 173720640014440, 1563485792415001, 14071372034879887
(list; graph; listen)
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OFFSET
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2,2
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REFERENCES
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J. Goldman and G.-C. Rota, The number of subspaces of a vector space, pp. 75-83 of W. T. Tutte, editor, Recent Progress in Combinatorics. Academic Press, NY, 1969.
I. P. Goulden and D. M. Jackson, Combinatorial Enumeration. Wiley, NY, 1983, p, 99.
M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.
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FORMULA
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G.f.: 1/[(1-x)(1+3x)(1-9x)].
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CROSSREFS
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Sequence in context: A069542 A063416 A043034 this_sequence A078246 A097184 A002296
Adjacent sequences: A015248 A015249 A015250 this_sequence A015252 A015253 A015254
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KEYWORD
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nonn,easy
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AUTHOR
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Olivier Gerard (ogerard(AT)ext.jussieu.fr)
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