%I #22 Jun 02 2022 10:09:38
%S 1,2,3,5,10,30,103,519
%N Number of diameter-2-critical graphs with n nodes.
%C The first 10 terms were obtained by filtering the list of non-isomorphic connected graphs, see McKay et al., 2013.
%H J. A. MacDougall and R. B. Eggleton, <a href="https://www.researchgate.net/publication/263930066_Triangle-free_and_Triangle-saturated_Graphs">Triangle-free and triangle-saturated Graphs</a>, Journal of Combinatorial Mathematics and Combinatorial Computing, 25:3-21, 1997.
%H B. D. McKay and A. Piperno, <a href="http://dx.doi.org/10.1016/j.jsc.2013.09.003">Practical Graph Isomorphism, II</a>, J. Symbolic Computation 60 (2013), 94-112.
%e The diameter-2-critical graphs for n=3,4,5 are K_{1,2}; K_{1,3}, C_4; K_{1,4}, K_{2,3}, C_5.
%K nonn,more
%O 3,2
%A _Miodrag Zivkovic_, Dec 17 2019