A120667 Number of n-node labeled bipartite graphs without isolated nodes.

1, 0, 1, 3, 22, 225, 3421, 73668, 2222977, 93033615, 5393456986, 433396737873, 48429436851577, 7548123580987080, 1646092439020192801, 503469306031901522043, 216430661498688457821022, 130959358877474026010486145, 111687660283090149155082836341

Offset

0,4

Links

Alois P. Heinz, Table of n, a(n) for n = 0..60

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

Adjacent sequences: A120664 A120665 A120666 * A120668 A120669 A120670

Keyword

easy,nonn

Author

Vladeta Jovovic, Jun 23 2007

Extensions

More terms from Alois P. Heinz, Sep 12 2008

Status

approved