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A014501
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Number of graphs with loops, having unlabeled (non-isolated) nodes and n labeled edges.
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2
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1, 2, 7, 43, 403, 5245, 89132, 1898630, 49209846, 1517275859, 54669946851, 2269075206395, 107199678164289, 5707320919486026, 339510756324234931, 22400182888853554291, 1628654713107465602783, 129754625253841669625051
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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REFERENCES
| G. Labelle, Counting enriched multigraphs..., Discrete Math., 217 (2000), 237-248.
G. Paquin, D\'enombrement de multigraphes enrichis, M\'emoire, Math. Dept., Univ. Qu\'ebec \`a Montr\'eal, 2004.
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FORMULA
| E.g.f.: exp(-1+x/2)*Sum((1+x)^binomial(n+1, 2)/n!, n=0..infinity) [probably in the Labelle paper] - Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 27 2004
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CROSSREFS
| Cf. A020554, A020555, A014500.
Sequence in context: A078676 A086331 A121418 * A197910 A011835 A198946
Adjacent sequences: A014498 A014499 A014500 * A014502 A014503 A014504
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KEYWORD
| nonn
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AUTHOR
| Simon Plouffe, gilbert(AT)lacim.uqam.ca (Gilbert Labelle).
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