

A024607


Number of connected trianglefree graphs on n unlabeled nodes.


12



1, 1, 1, 3, 6, 19, 59, 267, 1380, 9832, 90842, 1144061, 19425052, 445781050, 13743625184, 566756900370, 31125101479652
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OFFSET

1,4


LINKS

Table of n, a(n) for n=1..17.
P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.
Eric Weisstein's World of Mathematics, Connected Graph
Eric Weisstein's World of Mathematics, TriangleFree Graph


CROSSREFS

Inverse Euler transform of A006785. Table of graphs on n nodes with clique number k is A126744.
Column k=1 of A283417.
Sequence in context: A320174 A248603 A052393 * A186022 A058818 A184937
Adjacent sequences: A024604 A024605 A024606 * A024608 A024609 A024610


KEYWORD

hard,more,nonn,nice


AUTHOR

Peter J. Cameron


EXTENSIONS

2 more terms from Vladeta Jovovic, May 17 2008
2 more terms from A006785 by Martin Fuller, May 01 2015


STATUS

approved



