A076279 - OEIS

%I #22 Feb 16 2025 08:32:47

%S 0,0,1,3,16,84,579,5721,87381,2104349,78315231,4383566676,362178638727

%N Number of 3-chromatic (i.e., chromatic number equals 3) simple graphs on n nodes.

%H Keith M. Briggs, <a href="http://keithbriggs.info/cgt.html">Combinatorial Graph Theory</a>

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/n-ChromaticGraph.html">n-Chromatic Graph</a>

%Y Column k=3 of A084268.

%Y Cf. A076278, A076280, A076281, A076282, A115597.

%K nonn,more,changed

%O 1,4

%A _Eric W. Weisstein_, Oct 06 2002

%E a(10) from _Keith Briggs_, Mar 14 2006

%E a(11) from _Michael Sollami_, Jan 28 2012

%E a(12)-a(13) from _Brendan McKay_, Nov 08 2022