%I A084270
%S A084270 0,1,6,40,375,5176,103236,2922445,116011230,6433447396,498234407451,
%T A084270 54007795331920,8213123246906760,1756336596363006841,
%U A084270 528975889250504033526,224688018516023267969440,134708289561117007261966815
%N A084270 Number of labeled 2-chromatic (i.e. chromatic number = 2) graphs on n 
               nodes.
%H A084270 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               n-ChromaticGraph.html">n-Chromatic Graph</a>
%F A084270 a(n) = A047864(n)-1. - Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 31 
               2003
%Y A084270 Cf. A084271, A084272.
%Y A084270 Sequence in context: A014481 A000683 A143342 this_sequence A053677 A001367 
               A096671
%Y A084270 Adjacent sequences: A084267 A084268 A084269 this_sequence A084271 A084272 
               A084273
%K A084270 nonn
%O A084270 1,3
%A A084270 Eric Weisstein (eric(AT)weisstein.com), May 24, 2003
%E A084270 More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 31 2003
%E A084270 One further term from David Wasserman (wasserma(AT)spawar.navy.mil), 
               Dec 13 2004