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 A340687 #7 Jan 17 2021 11:23:41 %S A340687 3,21,51,177,354,852,1686,3036,5994,8550,12933,16938,24303,30192, %T A340687 41616,52581,66600,82857,101199,128409,153669,194505,227193,271635, %U A340687 320898,368703,431640,490884,578805,646869,744717,851214,943068,1071741,1195638,1367913,1523694,1713300,1885389,2082696 %N A340687 The number of edges on a concave circular triangle formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts. %C A340687 The terms are from numeric computation - no formula for a(n) is currently known. %C A340687 See A340685 for images of the regions and A340686 for images of the vertices. %H A340687 Wikipedia, <a href="https://en.wikipedia.org/wiki/Circular_triangle">Circular triangle</a>. %Y A340687 Cf. A340685 (regions), A340686 (vertices), A340688 (n-gons), A340613, A007678, A092867. %K A340687 nonn %O A340687 1,1 %A A340687 _Scott R. Shannon_ and _N. J. A. Sloane_, Jan 16 2021