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 A359975 #14 Jan 30 2023 10:33:44 %S A359975 1,5,30,110,479,993,3102,6135,12748,20680,43907,62753,118746,168892, %T A359975 246513,348176,571980,725956,1129035,1426393,1887096,2387945,3454566, %U A359975 4123548,5543837 %N A359975 Number of regions formed inside a right triangle by the straight line segments mutually connecting all vertices and points on the two shorter edges whose positions on one edge equal the Farey series of order n while on the other they divide its length into n equal segments. %C A359975 The number of vertices on the edge with point positions equaling the Farey series of order n is A005728(n). No formula for a(n) is known. %C A359975 This graph is related to the 'Farey fan' given in the reference. %D A359975 McIlroy, M. D. "A Note on Discrete Representation of Lines". AT&T Technical Journal, 64 (1985), 481-490. %H A359975 Scott R. Shannon, <a href="/A359975/a359975.jpg">Image for n = 2</a>. %H A359975 Scott R. Shannon, <a href="/A359975/a359975_1.jpg">Image for n = 3</a>. %H A359975 Scott R. Shannon, <a href="/A359975/a359975_2.jpg">Image for n = 4</a>. %H A359975 Scott R. Shannon, <a href="/A359975/a359975_3.jpg">Image for n = 5</a>. %H A359975 Scott R. Shannon, <a href="/A359975/a359975_4.jpg">Image for n = 6</a>. %F A359975 a(n) = A359976(n) - A359974(n) + 1 by Euler's formula. %Y A359975 Cf. A359974 (vertices), A359976 (edges), A359977 (k-gons), A005728, A359969, A359690, A358948, A358886. %K A359975 nonn,more %O A359975 1,2 %A A359975 _Scott R. Shannon_ and _N. J. A. Sloane_, Jan 20 2023