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%I #7 Jan 12 2023 16:13:26
%S 1,7,59,275,1949,3971,20333,45705,120899,205233,629761,897707,2334291,
%T 3461329,5516985,8467899
%N 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 The number of vertices along each edge is A005728(n). No formula for a(n) is known.
%C See A359690 for images of the graph.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CompleteBipartiteGraph.html">Complete Bipartite Graph</a>.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Farey_sequence">Farey sequence</a>.
%F a(n) = A359690(n) - 2*A005728(n).
%Y Cf. A359690 (vertices), A359692 (regions), A359693 (edges), A359694 (k-gons), A005728, A159065, A331755, A359654, A358887, A358883, A006842, A006843.
%K nonn,more
%O 1,2
%A _Scott R. Shannon_ and _N. J. A. Sloane_, Jan 11 2023
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