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 A334458 #14 Jun 02 2025 22:32:41 %S A334458 1,4,12,39,125,271,609,1076,1884,2950,4642,6541,9607,12969,17505, %T A334458 23034,30294,37888,48488,59404,73506,88779,108077,127412,153000, %U A334458 178514,210366,242961,283243,322120,373147,422454,482442,542604,615300,685885,773189,857791 %N A334458 Number of vertices in a polygon whose boundary consists of n+2 equally spaced points around a semicircle and n+2 equally spaced points along the diameter (a total of 2n+2 points). See Comments for precise definition. %C A334458 A semicircular polygon with 2n+2 points is created by placing n+2 equally spaced vertices along the semicircle's arc (including the two end vertices). Also place n+2 equally spaced vertices along the diameter (again including the same two end vertices). Now connect every pair of vertices by a straight line segment. The sequence gives the number of vertices in the resulting figure. %H A334458 Lars Blomberg, <a href="/A334458/b334458.txt">Table of n, a(n) for n = 0..50</a> %Y A334458 Cf. A333519, A334459 %K A334458 nonn %O A334458 0,2 %A A334458 _Lars Blomberg_, May 01 2020