A128240 Number of n-node (unlabeled) connected graphs with girth 3.

0, 0, 1, 3, 15, 93, 794, 10850, 259700, 11706739, 1006609723, 164058686415, 50335888444167, 29003487017067011, 31397381129017616776, 63969560112658419275907, 245871831682052901418048916

Offset: 1

Author

Keith Briggs, May 05 2007

Keywords

• nonn

Comments

Number of unlabeled, connected graphs on n vertices with at least one induced subgraph isomorphic to a K_3, where K_3 is the complete graph on three vertices (a triangle). - Travis Hoppe and Anna Petrone, Jun 01 2014

Links

• Travis Hoppe and Anna Petrone, Encyclopedia of Finite Graphs
• T. Hoppe and A. Petrone, Integer sequence discovery from small graphs, arXiv preprint arXiv:1408.3644 [math.CO], 2014
• Eric Weisstein's World of Mathematics, Triangle-Free Graph

Crossrefs

a(n) = A001349(n) - A024607(n).

Cf. A128041, A128042, A128236-A128243.

Extensions

Corrected and extended by Martin Fuller, May 01 2015

Information added by Falk Hüffner, Nov 27 2015