This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A280020 #23 Jul 25 2019 04:35:48
%S A280020 1,1,3,7,27,211,1743,15247,219747,5379451,154297863,5085738967,
%T A280020 225515577147,14272681411171
%N A280020 Number of maximal triangle-free labeled graphs on n vertices.
%H A280020 József Balogh, Šárka Petříčková, <a href="https://arxiv.org/abs/1409.8123">The number of the maximal triangle-free graphs</a>, Bull. London Math. Soc., 46 (2014), 1003-1006.
%H A280020 F. Hüffner, <a href="https://github.com/falk-hueffner/tinygraph">tinygraph</a>, software for generating integer sequences based on graph properties.
%e A280020 For n = 1 the only graph is the graph with one node and no edges. For n = 2 the only graph is the complete graph K_2. For n = 3 the maximal triangle-free graphs are isomorphic to the complete bipartite graph K_{2,1}.
%Y A280020 Cf. A000514.
%Y A280020 Cf. A216783 (unlabeled graphs).
%K A280020 nonn,more
%O A280020 1,3
%A A280020 _Roland Hildebrand_, Feb 22 2017
%E A280020 a(11)-a(14) added using tinygraph by _Falk Hüffner_, Jul 24 2019