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Search: id:A117279
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| A117279 |
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Triangle read by rows: T(n,k) is number of labeled bipartite graphs with n nodes and k edges. |
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+0
1
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| 1, 1, 1, 1, 1, 3, 3, 1, 6, 15, 16, 3, 1, 10, 45, 110, 140, 60, 10, 1, 15, 105, 435, 1125, 1701, 1200, 480, 105, 10, 1, 21, 210, 1295, 5355, 14952, 26572, 26670, 17535, 7840, 2331, 420, 35, 1, 28, 378, 3220, 19075, 81228, 246414, 507424, 666015, 620900, 431368
(list; graph; listen)
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OFFSET
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0,6
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REFERENCES
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R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Problem 5.5.
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FORMULA
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E.g.f.: sqrt(Sum_{n>=0} exp(x*(1+q)^n)*x^n/n!).
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EXAMPLE
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1; 1; 1,1; 1,3,3; 1,6,15,16,3; 1,10,45,110,140,60,10; ...
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CROSSREFS
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Cf. A047864, A000217, A050534, A053526, A053527, A053528, A052296, A033995.
Sequence in context: A039798 A001498 A138464 this_sequence A049323 A084144 A116401
Adjacent sequences: A117276 A117277 A117278 this_sequence A117280 A117281 A117282
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KEYWORD
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nonn,tabf
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AUTHOR
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Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 23 2007
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