%I #11 May 08 2018 03:56:28
%S 1,2,4,10,29,120,685,6431,103164,2894632,138892304,11118977705,
%T 1459412127955
%N Number of simple graphs with n vertices which contain no K4 subgraph.
%C The graphs do not need to be connected.
%F a(n) = 1+A052450(n)+A052451(n).
%Y Cf. A000088, A006785 (no K3), A115196 (graphs by clique number), A304125 (no K5).
%K nonn,more
%O 1,2
%A _Brendan McKay_, May 06 2018
%E a(13) from _Brendan McKay_, May 08 2018