A128240 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

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

Table of n, a(n) for n=1..17.

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.

Sequence in context: A308457 A241711 A243245 * A369270 A369301 A368964

Adjacent sequences: A128237 A128238 A128239 * A128241 A128242 A128243

KEYWORD

nonn

AUTHOR

Keith Briggs, May 05 2007

EXTENSIONS

Corrected and extended by Martin Fuller, May 01 2015

Information added by Falk Hüffner, Nov 27 2015

STATUS

approved