Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #14 Jan 15 2016 11:27:10
%S 0,0,0,0,1,7,129,3312,134303,8594350,894307856,158323596832
%N Number of simple connected imperfect graphs on n vertices.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ImperfectGraph.html">Imperfect Graph.</a>
%F a(n) = A001349(n) - A052433(n).
%Y Cf. A001349, A052433, A187236.
%K nonn,more,hard
%O 1,6
%A _Eric W. Weisstein_, Mar 07 2011
%E a(12) using formula by _Falk Hüffner_, Jan 15 2016