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A020559
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Number of ordered multigraphs on n labeled edges (with loops).
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0
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1, 2, 11, 97, 1219, 20385, 433022, 11296844, 352866598, 12938878499, 548257129281, 26503637228615, 1446212232918009, 88278080019931590, 5981590442549971867, 446907535344317788261, 36602523445840041088223
(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((3*x-2)/(2-2*x))*Sum(1/(n!*(1-x)^binomial(n+1, 2)), n = 0 .. infinity). - Vladeta Jovovic (vladeta(AT)eunet.rs), May 02 2004
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CROSSREFS
| Cf. A020558.
Sequence in context: A136344 A055680 A166909 * A003579 A099169 A143135
Adjacent sequences: A020556 A020557 A020558 * A020560 A020561 A020562
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KEYWORD
| nonn
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AUTHOR
| Gilbert Labelle (gilbert(AT)lacim.uqam.ca), Simon Plouffe (simon.plouffe(AT)gmail.com)
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