%I #9 Jan 15 2023 01:45:13
%S 1,2,6,16,78,415,3374,35860,524386,10193061,263036202,8948113645,
%T 400280198048
%N Number of 2-connected unlabeled simple graphs with no triangles.
%e For n=4 the only example is a 4-cycle.
%Y Cf. A002218 all 2-connected graphs.
%Y Cf. A024607 all connected triangle-free graphs.
%K nonn,hard,more
%O 4,2
%A _Brendan McKay_, Jun 12 2021