%I #13 Jan 12 2023 16:12:08
%S 5,13,69,289,1971,3997,20371,45751,120957,205299,629847,897801,
%T 2334409,3461459,5517131,8468061
%N Number of vertices 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.
%H Scott R. Shannon, <a href="/A359690/a359690.png">Image for n = 1</a>.
%H Scott R. Shannon, <a href="/A359690/a359690_1.png">Image for n = 2</a>.
%H Scott R. Shannon, <a href="/A359690/a359690_2.png">Image for n = 3</a>.
%H Scott R. Shannon, <a href="/A359690/a359690_3.png">Image for n = 4</a>.
%H Scott R. Shannon, <a href="/A359690/a359690_4.png">Image for n = 5</a>.
%H Scott R. Shannon, <a href="/A359690/a359690_5.png">Image for n = 6</a>.
%H Scott R. Shannon, <a href="/A359690/a359690_6.png">Image for n = 7</a>.
%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) = A359693(n) - A359692(n) + 1 by Euler's formula.
%Y Cf. A359691 (crossings), A359692 (regions), A359693 (edges), A359694 (k-gons), A005728, A331755, A359654, A358887, A358883, A006842, A006843.
%K nonn,more
%O 1,1
%A _Scott R. Shannon_ and _N. J. A. Sloane_, Jan 11 2023