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%I #10 Jan 12 2023 16:13:39
%S 2,12,94,382,2486,4946,24100,53152,138158,233254,700720,999364,
%T 2559344,3785044,6027148,9210820
%N Number of regions 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="/A359692/a359692.jpg">Image for n = 1</a>.
%H Scott R. Shannon, <a href="/A359692/a359692_1.jpg">Image for n = 2</a>.
%H Scott R. Shannon, <a href="/A359692/a359692_2.jpg">Image for n = 3</a>.
%H Scott R. Shannon, <a href="/A359692/a359692_3.jpg">Image for n = 4</a>.
%H Scott R. Shannon, <a href="/A359692/a359692_4.jpg">Image for n = 5</a>.
%H Scott R. Shannon, <a href="/A359692/a359692_5.jpg">Image for n = 6</a>.
%H Scott R. Shannon, <a href="/A359692/a359692_6.jpg">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) - A359690(n) + 1 by Euler's formula.
%Y Cf. A359690 (vertices), A359691 (crossings), A359693 (edges), A359694 (k-gons), A005728, A290131, A359653, A358886, A358882, A006842, A006843.
%K nonn
%O 1,1
%A _Scott R. Shannon_ and _N. J. A. Sloane_, Jan 11 2023