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A120667
Number of n-node labeled bipartite graphs without isolated nodes.
1
1, 0, 1, 3, 22, 225, 3421, 73668, 2222977, 93033615, 5393456986, 433396737873, 48429436851577, 7548123580987080, 1646092439020192801, 503469306031901522043, 216430661498688457821022, 130959358877474026010486145, 111687660283090149155082836341
OFFSET
0,4
LINKS
FORMULA
E.g.f.: sqrt( e.g.f. for A052332 ) = sqrt(Sum_{n>=0} exp(x*(2^n-2)) * x^n/n!).
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
CROSSREFS
Cf. A047864.
Sequence in context: A303190 A173142 A073530 * A196958 A274246 A161567
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Jun 23 2007
EXTENSIONS
More terms from Alois P. Heinz, Sep 12 2008
STATUS
approved