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 A374339 #12 Jul 06 2024 09:23:10 %S A374339 6,18,40,78,132,190,264,354,448,558,684,814,960,1122,1288,1470,1668, %T A374339 1870,2088,2322,2560,2814,3084,3358,3648,3954,4264,4590,4932,5278, %U A374339 5640,6018,6400,6798,7212,7630,8064,8514,8968,9438,9924,10414,10920,11442,11968,12510,13068,13630,14208,14802 %N A374339 Start with two vertices and draw a circle around each whose radius is the distance between the vertices. The sequence gives the number of curved edges constructed after n iterations of drawing circles with this same radius around every new vertex created from all circles' intersections. %C A374339 See A374338 for further details and images. %F A374339 a(n) = A374337(n) + A374338(n) - 1, by Euler's formula. %Y A374339 Cf. A374337 (regions), A374338 (vertices), A359571, A371375, A371255. %K A374339 nonn %O A374339 1,1 %A A374339 _Scott R. Shannon_, Jul 05 2024