

A010357


Number of unlabeled nonseparable (or 2connected) multigraphs with n edges.


3



1, 1, 2, 3, 6, 14, 32, 90, 279, 942, 3468, 13777, 57747, 254671, 1170565, 5580706, 27487418, 139477796, 727458338, 3893078684
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OFFSET

1,3


COMMENTS

Original name: Multiedge stars with n edges.


LINKS

Table of n, a(n) for n=1..20.
George A. Baker Jr. and John M. Kincaid, The continuousspin Ising model, g0:phi4:d field theory and the renormalization group. J. Statist. Phys. 24 (1981), no. 3, 469528.
Brendan McKay and Adolfo Piperno, nauty and Traces, programs for computing automorphism groups of graphs and digraphs.
Gus Wiseman, Nonisomorphic representatives of the a(1) = 1 through a(6) = 14 unlabeled 2connected multigraphs.


EXAMPLE

From Andrew Howroyd, Nov 23 2020: (Start)
The a(1) = 1 graph is a single edge (K_2 = P_2).
The a(2) = 1 graph is a double edge.
The a(3) = 2 graphs are a triple edge and the triangle (K_3).
The a(4) = 3 graphs are a quadruple edge, a triangle with one double edge and the square (C_4).
(End)


CROSSREFS

Row sums of A339160.
Cf. A050535, A076864, A010355, A010359.
A002218 counts unlabeled 2connected graphs.
A013922 counts labeled 2connected graphs.
A322140 is a labeled version.
Cf. A002905, A006444, A007718, A275307, A304887.
Sequence in context: A099968 A291401 A331875 * A190166 A238823 A002995
Adjacent sequences: A010354 A010355 A010356 * A010358 A010359 A010360


KEYWORD

nonn,more


AUTHOR

N. J. A. Sloane


EXTENSIONS

Name changed by Andrew Howroyd, Dec 05 2020
a(11)a(20) added using geng/multig from nauty by Andrew Howroyd, Dec 05 2020


STATUS

approved



