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 A306180 #7 Jun 25 2018 12:46:22 %S A306180 1,5,23,169,1233,9551 %N A306180 Number of unrooted self-avoiding walks with n steps that can make turns from the set 0, +-Pi/5, +-2*Pi/5, +-3*Pi/5, +-4*Pi/5. %C A306180 The turning angles are those of the regular decagon, with one vertex corresponding to the forbidden U-turn. The path may neither intersect nor touch itself anywhere. %H A306180 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 A306180 Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/a306180.htm">Illustration of walks of lengths <= 3</a>. %Y A306180 Cf. A266925, A037245, A306175, A151541, A306177, A306178, A306179, A306181, A306182. %K A306180 nonn,walk,more %O A306180 1,2 %A A306180 _Hugo Pfoertner_, Jun 23 2018