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 A316197 #6 Jul 02 2018 20:27:14 %S A316197 0,0,3,4,83,533,8329 %N A316197 Number of self-avoiding polygons with perimeter 2*n and sides = 1 that have vertex angles from the set +-Pi/7, +-3*Pi/7, +-5*Pi/7, not counting rotations and reflections as distinct. %H A316197 Contest Organizers, <a href="http://www.recmath.org/contest/Snakes/index.php">Al Zimmermann's Programming Contests - Snakes on a Plane</a>, Fall 2006. %H A316197 Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/a316197.htm">Illustration of polygons of perimeter <= 12</a>. %Y A316197 Cf. A306177, A258206, A266549, A284869, A316195. %K A316197 nonn,walk,more %O A316197 1,3 %A A316197 _Hugo Pfoertner_, Jun 28 2018