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 A316200 #5 Jul 07 2018 19:29:37 %S A316200 0,0,0,2,2,10,15,124,352,2378,19405 %N A316200 Number of self-avoiding polygons with perimeter n and sides = 1 that have vertex angles from the set 0, +-Pi/5, +-2*Pi/5, +-3*Pi/5, +-4*Pi/5, not counting rotations and reflections as distinct. %C A316200 Holes are excluded, i.e., the boundary path may nowhere touch or intersect itself. %H A316200 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 A316200 Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/a316200.htm">Illustration of polygons of perimeter <= 9</a>. %Y A316200 Cf. A258206, A266549, A284869, A306180, A316192, A316195, A316197, A316198, A316199, A316201. %K A316200 nonn,walk,more %O A316200 1,4 %A A316200 _Hugo Pfoertner_, Jul 07 2018