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A098634
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Consider the family of multigraphs enriched by the species of even sets. Sequence gives number of those multigraphs with 2n loops and arcs.
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1, 2, 41, 2627, 357716, 86570987, 33355085381, 19002804068432, 15177169622020811, 16322141415741150887, 22901431199026692596006, 40870032497467496395428677, 90848469347406506760349066541, 247166310906569012786184536033402, 810867121877912775078998948740650941
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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REFERENCES
| 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)*sum(cosh(x)^(n^2)/n!,n = 0 .. infinity). - Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 04 2008
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CROSSREFS
| Sequence in context: A133298 A054742 A113634 * A193270 A076391 A130201
Adjacent sequences: A098631 A098632 A098633 * A098635 A098636 A098637
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Oct 26 2004
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EXTENSIONS
| More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 04 2008
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