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A267602 Number of unlabeled, connected graphs on n vertices that are prime and have no induced subgraph isomorphic to a bull, a P5 or a P5-bar. 1

%I #10 Jan 20 2016 04:19:21

%S 0,0,0,1,1,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,

%T 0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,

%U 0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0

%N Number of unlabeled, connected graphs on n vertices that are prime and have no induced subgraph isomorphic to a bull, a P5 or a P5-bar.

%C a(4) = 1 is the P_4, a(5) = 1 is the C_5, and a(n) = 2 for even n >= 6 are the unique prime bipartite chain graph on n vertices and its complement. - _Falk Hüffner_, Jan 18 2016

%H J. L. Fouquet, <a href="http://dx.doi.org/10.1016/0012-365X(93)90539-6">A Decomposition for a class of (P5,P5-bar)-free graphs</a>, Discrete Math. 121 (1993) 75-83.

%Y Cf. A079577 (without "prime" requirement)

%K nonn,easy

%O 1,6

%A _Falk Hüffner_, Jan 18 2016

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