

A095983


Number of 2edgeconnected labeled graphs on n nodes.


17



0, 0, 0, 1, 10, 253, 11968, 1047613, 169181040, 51017714393, 29180467201536, 32121680070545657, 68867078000231169536, 290155435185687263172693, 2417761175748567327193407488, 40013922635723692336670167608181, 1318910073755307133701940625759574016
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OFFSET

0,5


COMMENTS

From Falk Hüffner, Jun 28 2018: (Start)
Equivalently, number of connected bridgeless labeled graphs (graphs that are kedge connected for k >= 2).
Labeled version of A007146. (End)


LINKS

Table of n, a(n) for n=0..16.


PROG

(PARI) \\ here p is initially A053549, q is A198046 as e.g.f's.
seq(n)={my(v=vector(n));
my(p=x*deriv(log(sum(k=0, n, 2^binomial(k, 2) * x^k / k!) + O(x*x^n))));
my(q=x*exp(p)); p=q;
for(k=3, n, my(c=polcoeff(p, k)); v[k]=c*(k1)!; p=c*q^k);
concat([0], v)} \\ Andrew Howroyd, Jun 18 2018


CROSSREFS

Cf. A013922, A053549, A198046.
Sequence in context: A001536 A114450 A178689 * A059166 A100743 A251588
Adjacent sequences: A095980 A095981 A095982 * A095984 A095985 A095986


KEYWORD

nonn


AUTHOR

Yifei Chen (yifei(AT)mit.edu), Jul 17 2004


EXTENSIONS

Name corrected and extended by Pavel Irzhavski, Nov 01 2014
Offset corrected by Falk Hüffner, Jun 17 2018
a(12)a(16) from Andrew Howroyd, Jun 18 2018


STATUS

approved



