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.

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, 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, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0

Offset: 1

Author

Falk Hüffner, Jan 18 2016

Keywords

• nonn
• easy

Comments

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

Links

• J. L. Fouquet, A Decomposition for a class of (P5,P5-bar)-free graphs, Discrete Math. 121 (1993) 75-83.

Crossrefs

Cf. A079577 (without "prime" requirement)