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 A306177 #12 May 15 2025 16:05:17 %S A306177 1,3,11,55,275,1444,7609,40220,212051,1114206,5840287,30521627, %T A306177 159166728,828130291,4301636648 %N A306177 Number of unrooted self-avoiding walks with n steps that can make turns from the set +-Pi/7, +-3*Pi/7, +-5*Pi/7. %C A306177 The turning angles are those of the regular heptagon, with one vertex corresponding to the forbidden U-turn. The path may neither intersect nor touch itself anywhere. %H A306177 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 A306177 Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/a306177.htm">Illustration of walks of lengths <= 4</a>. %Y A306177 Cf. A266925, A037245, A306175, A151541, A306178, A306179, A306180, A306181, A306182. %K A306177 nonn,walk,more %O A306177 1,2 %A A306177 _Hugo Pfoertner_, Jun 23 2018 %E A306177 a(7)-a(15) from _Bert Dobbelaere_, May 15 2025