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A120667
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Number of n-node labeled bipartite graphs without isolated nodes.
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1
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1, 0, 1, 3, 22, 225, 3421, 73668, 2222977, 93033615, 5393456986, 433396737873, 48429436851577, 7548123580987080, 1646092439020192801, 503469306031901522043, 216430661498688457821022, 130959358877474026010486145, 111687660283090149155082836341
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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LINKS
| Alois P. Heinz, Table of n, a(n) for n = 0..60
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FORMULA
| E.g.f.: sqrt( e.g.f. for A052332 ) = sqrt(Sum_{n>=0} exp(x*(2^n-2))*x^n/n!).
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MAPLE
| a:= n-> coeff (series (sqrt (add (exp (x*(2^k-2)) *x^k/k!, k=0..n)), x, n+1), x, n)*n!: seq (a(n), n=0..20); # Alois P. Heinz, Sep 12 2008
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CROSSREFS
| Cf. A047864.
Sequence in context: A141152 A173142 A073530 * A196958 A161567 A141006
Adjacent sequences: A120664 A120665 A120666 * A120668 A120669 A120670
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KEYWORD
| easy,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 23 2007
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EXTENSIONS
| More terms from Alois P. Heinz (heinz(AT)hs-heilbronn.de), Sep 12 2008
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