

A242790


Number of connected diamondfree graphs on n nodes.


11



1, 1, 2, 4, 11, 39, 165, 967, 7684, 87012, 1410465, 32640019
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OFFSET

1,3


COMMENTS

An equivalent definition: Number of simple connected graphs with n nodes that are have no subgraph isomorphic to the diamond graph or the complete graph K_4. This is the same because a graph contains a diamond as a subgraph iff it contains a diamond or K_4 as induced subgraph.  Falk Hüffner, Jan 11 2015


LINKS

Table of n, a(n) for n=1..12.
Travis Hoppe and Anna Petrone, Encyclopedia of Finite Graphs
Falk Hüffner, tinygraph, software for generating integer sequences based on graph properties, version ece94ef.
Eric Weisstein's World of Mathematics, Diamond Graph


CROSSREFS

Cf. A077269 (connected squarefree graphs).
Cf. also A242790 (diamond free graphs), A079574 (K_4 free graphs).
Sequence in context: A216810 A065851 A173938 * A013044 A110577 A335441
Adjacent sequences: A242787 A242788 A242789 * A242791 A242792 A242793


KEYWORD

nonn,more


AUTHOR

Travis Hoppe and Anna Petrone, May 22 2014


EXTENSIONS

Entry revised by N. J. A. Sloane, Jan 11 2016
a(11) and a(12) added using tinygraph by Falk Hüffner, Jan 15 2016


STATUS

approved



