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Search: id:A121251
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| A121251 |
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Number of labeled graphs without isolated vertices and with n edges. |
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+0
4
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| 1, 1, 6, 62, 900, 16824, 384668, 10398480, 324420840, 11472953760, 453518054216, 19815916826160, 948348447031440, 49334804947402800, 2771902062752597520, 167281797371598801136, 10791777047497882651296, 741135302021991803931360
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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a(n)~ C0*(C1*n)^n, where C0 = 1/2^(1+ln(2)/4)/ln(2) = .63970540489176946794... and C1 = 2/(ln(2))^2/exp(1) = 1.5313857152078346894..., [Bender et al.]
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REFERENCES
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E. A. Bender and E. R. Canfield and B. D. McKay, The asymptotic number of labeled graphs with n vertices, q edges, and no isolated vertices, J Combinatorial Theory, Series A, 80 (1997) 124-150.
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LINKS
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E. A. Bender and E. R. Canfield and B. D. McKay, The asymptotic number of labeled graphs with n vertices, q edges, and no isolated vertices.
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FORMULA
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a(n) = Sum_{m>=0} binomial(binomial(m,2),n)/2^(m+1). Column sums of A054548.
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CROSSREFS
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Cf. A006129.
Sequence in context: A127695 A022517 A022502 this_sequence A055005 A027811 A027950
Adjacent sequences: A121248 A121249 A121250 this_sequence A121252 A121253 A121254
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 22 2006, Sep 19 2006
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EXTENSIONS
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More terms from Max Alekseyev, Aug 23 2006
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