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 A316195 #11 Jul 03 2018 04:18:08 %S A316195 0,0,2,1,18,45,441 %N A316195 Number of self-avoiding polygons with perimeter 2*n and sides = 1 that have vertex angles from the set +-Pi/5, +-3*Pi/5, not counting rotations and reflections as distinct. %C A316195 Holes are excluded, i.e., the boundary path may nowhere touch or intersect itself. %H A316195 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 A316195 Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/a316195.htm">Illustration of polygons of perimeter <= 14</a>. %Y A316195 Cf. A306175, A258206, A266549, A284869. %K A316195 nonn,walk,more %O A316195 1,3 %A A316195 _Hugo Pfoertner_, Jun 26 2018