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