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 A359691 #8 Feb 16 2025 08:34:04 %S A359691 1,7,59,275,1949,3971,20333,45705,120899,205233,629761,897707,2334291, %T A359691 3461329,5516985,8467899 %N A359691 Number of crossings in a regular drawing of a complete bipartite graph where the vertex positions on each part equal the Farey series of order n. %C A359691 The number of vertices along each edge is A005728(n). No formula for a(n) is known. %C A359691 See A359690 for images of the graph. %H A359691 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CompleteBipartiteGraph.html">Complete Bipartite Graph</a>. %H A359691 Wikipedia, <a href="https://en.wikipedia.org/wiki/Farey_sequence">Farey sequence</a>. %F A359691 a(n) = A359690(n) - 2*A005728(n). %Y A359691 Cf. A359690 (vertices), A359692 (regions), A359693 (edges), A359694 (k-gons), A005728, A159065, A331755, A359654, A358887, A358883, A006842, A006843. %K A359691 nonn,more %O A359691 1,2 %A A359691 _Scott R. Shannon_ and _N. J. A. Sloane_, Jan 11 2023