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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
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,6
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)
Sequence in context: A101227 A277162 A230103 * A021499 A176742 A010673
KEYWORD
nonn,easy
AUTHOR
Falk Hüffner, Jan 18 2016
STATUS
approved

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Last modified April 15 20:47 EDT 2024. Contains 371696 sequences. (Running on oeis4.)