

A213434


a(n) is the number of labeled trianglefree simple graphs on n vertices.


2



1, 2, 7, 41, 388, 5789, 133501, 4682270, 246348115, 19213627145, 2198376297964, 365587270414697, 87628189849380625, 30044424979717359410, 14633141237888767056799, 10059886640779846047089825
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OFFSET

1,2


COMMENTS

Former name: Number of n X n symmetric binary matrices with zero diagonal and no threenode loops x(i,j)*x(j,k)*x(k,i) = 1, i < j < k.


LINKS

Falk Hüffner, tinygraph, software for generating integer sequences based on graph properties, version 8c665c7


EXAMPLE

Some solutions for n=4:
0 1 0 0 0 1 1 0 0 1 0 0 0 0 1 1 0 1 0 0
1 0 1 0 1 0 0 1 1 0 0 0 0 0 1 0 1 0 0 1
0 1 0 1 1 0 0 1 0 0 0 1 1 1 0 0 0 0 0 0
0 0 1 0 0 1 1 0 0 0 1 0 1 0 0 0 0 1 0 0


CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS

a(11)a(13) added using tinygraph by Falk Hüffner, Jun 19 2018
a(14)a(15) added using tinygraph by Falk Hüffner, Oct 28 2019


STATUS

approved



