

A120412


Number of different graphs with n = number of vertices plus number of edges.


0



1, 1, 2, 2, 3, 5, 7, 10, 16, 25, 40, 66, 111
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OFFSET

1,3


COMMENTS

Given two integers p, q, one can count the number of different graphs having p vertices and q edges by the standard Polya counting technique. Our sequence is then obtained by summing up the terms with p+q=n.


LINKS

Table of n, a(n) for n=1..13.


EXAMPLE

a(3) = 2 because there is a graph with 3 vertices and no edges and a graph with 2 vertices and one edge.


CROSSREFS

Sequence in context: A097333 A001083 A173696 * A022864 A039894 A133225
Adjacent sequences: A120409 A120410 A120411 * A120413 A120414 A120415


KEYWORD

nonn


AUTHOR

Petr Vojtechovsky (petr(AT)math.du.edu), Jul 05 2006


STATUS

approved



