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%I #6 Dec 03 2018 15:35:17
%S 0,0,1,3,5,10,15,26,37,58
%N Number of graphs on n nodes with edge chromatic number 2.
%H Keith M. Briggs, <a href="http://keithbriggs.info/cgt.html">Combinatorial Graph Theory</a>
%Y A diagonal of triangle in A123962.
%K nonn
%O 1,4
%A _N. J. A. Sloane_, Feb 16 2007