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 A290866 #12 Feb 19 2020 22:34:13 %S A290866 0,1,3,8,20,45,91,168,285,450,670,981,1375,1902,2568,3371,4326,5522, %T A290866 6927,8639,10624,12882,15489,18559,22006,25904,30321,35254,40728, %U A290866 46959,53721,61354,69734,78917,89029,100018,111758,124759,138943 %N A290866 a(n) = number of segments (edges) in the configuration A290447(n). %C A290866 Only edges above the line are counted. Total edges = a(n) + n - 1. %H A290866 David Applegate, <a href="/A290866/b290866.txt">Table of n, a(n) for n = 1..100</a> %F A290866 a(n) = A290447(n) + A290865(n). %Y A290866 Cf. A290447, A290865, A290867. %K A290866 nonn %O A290866 1,3 %A A290866 _David Applegate_, Aug 12 2017