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A058381
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Number of series-parallel networks with n labeled edges, multiple edges not allowed.
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5
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0, 1, 1, 4, 20, 156, 1472, 17396, 239612, 3827816, 69071272, 1394315088, 31081310944, 758901184432, 20135117147056, 576927779925568, 17752780676186432, 583910574851160000, 20443098012485430272, 759064322969950283072
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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REFERENCES
| J. W. Moon, Some enumerative results on series-parallel networks, Annals Discrete Math., 33 (1987), 199-226 (the sequence V_n).
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LINKS
| Index entries for sequences mentioned in Moon (1987)
S. R. Finch, Series-parallel networks
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FORMULA
| E.g.f.: -2*LambertW(-1/2*exp(-1/2)*(1+x)^(1/2))-1. - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 21 2006
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CROSSREFS
| Equals A058379 + A058380.
Sequence in context: A119022 A006682 A115852 * A094651 A065526 A032333
Adjacent sequences: A058378 A058379 A058380 * A058382 A058383 A058384
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KEYWORD
| nonn,nice,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Dec 19 2000
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