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%I #14 Jan 16 2016 10:33:03
%S 1,2,4,11,27,78,218,653,1963,6088,19078,60825,195757,636810,2087764,
%T 6896119
%N Number of P_4-sparse perfect graphs on n nodes.
%C A graph is P_4-sparse if no set of 5 vertices induces a subgraph that contains two or more induced P_4 (path on 4 vertices). P4-sparse graphs are perfect. - _Falk Hüffner_, Dec 01 2015
%D C. T. Hoàng, Perfect graphs, Ph.D. Thesis, School of Computer Science, McGill University, Montreal, Canada, 1985.
%H S. Hougardy, <a href="http://www.or.uni-bonn.de/~hougardy/">Home Page</a>
%H S. Hougardy, <a href="http://dx.doi.org/10.1016/j.disc.2006.05.021">Classes of perfect graphs</a>, Discr. Math. 306 (2006), 2529-2571.
%H F. Hüffner, <a href="https://github.com/falk-hueffner/tinygraph">tinygraph</a>, software for generating integer sequences based on graph properties, version 5926e72.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Oct 18 2006
%E a(11)-a(16) added using tinygraph by _Falk Hüffner_, Jan 16 2016