%I #12 Mar 05 2020 23:53:53
%S 0,0,0,0,0,0,0,0,0,0,1,23,1085,75127,6384013
%N Number of connected triangle-free graphs on n nodes with chromatic number 4.
%H Keith M. Briggs, <a href="http://keithbriggs.info/cgt.html">Combinatorial Graph Theory</a>
%Y See A116079 for further information.
%K nonn
%O 1,12
%A _N. J. A. Sloane_
%E a(15) from _Michael Sollami_, Feb 04 2012