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%I #6 Dec 19 2022 13:31:51
%S 3,21,375,2574,22083,52791,279750,673050,1851816,3272058,9865560,
%T 14592537
%N Number of edges formed inside a triangle with edge length 1 by the straight line segments mutually connecting all vertices and points that divide the sides into segments with lengths equal to the Farey series of order n = A006842(n,k)/A006843(n,k), k = 1..A005728(n).
%C The number of points along each edge is given by A005728(n).
%C See A358948 and A358949 for images of the square.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Farey_sequence">Farey sequence</a>.
%F a(n) = A358948(n) + A358949(n) - 1 by Euler's formula.
%Y Cf. A358948 (regions), A358949 (vertices), A358951 (k-gons), A358888, A006842, A006843, A005728, A358882.
%K nonn,more
%O 1,1
%A _Scott R. Shannon_ and _N. J. A. Sloane_, Dec 07 2022