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 A290667 #21 Jul 25 2019 04:34:17 %S A290667 0,0,0,1,4,19,84,378,1727,8126,39055,191902,960681 %N A290667 Number of asymmetric equicolorable (unrooted) trees with 2*n vertices. %C A290667 Any tree with 2n vertices is a bipartite graph with s vertices in one part and t vertices in the other part, where s <= t and s + t = 2n. We count trees with s = t = n, and which are asymmetric, that is, their only automorphism is the identity automorphism. These are also called identity trees. %D A290667 R. C. Read and R. J. Wilson, Atlas of Graphs, Oxford Science Publications, Clarendon Press, OUP, 2004. %H A290667 F. Hüffner, <a href="https://github.com/falk-hueffner/tinygraph">tinygraph</a>, software for generating integer sequences based on graph properties. %H A290667 Austin Mohr, <a href="http://austinmohr.com/home/?page_id=1422">Unlabeled Trees</a>. %e A290667 a(3) = 0 because there are six trees with 6 vertices, but only three of these have s = t = n = 3, and none of these three is asymmetric. The fourth term a(4) = 1 because there are nine trees with 8 vertices with s = t = n = 4 but only 1 is asymmetric, namely tree T46. See "Atlas of Graphs", page 65. %Y A290667 Cf. A119856 (equicolorable trees with 2n vertices), A000220 (asymmetric trees with n vertices). %K A290667 nonn,more %O A290667 1,5 %A A290667 _John P. McSorley_, Aug 08 2017 %E A290667 a(10)-a(13) added using tinygraph by _Falk Hüffner_, Jul 25 2019