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 A306178 #10 May 15 2025 12:34:13 %S A306178 1,4,15,86,492,2992,18172,110643,672267,4069122,24578785,147972210, %T A306178 889332713,5331980703,31924424199 %N A306178 Number of unrooted self-avoiding walks with n steps that can make turns from the set 0, +-Pi/4, +-Pi/2, +-3*Pi/4. %C A306178 The turning angles are those of the regular octagon, with one vertex corresponding to the forbidden U-turn. The path may neither intersect nor touch itself anywhere. %H A306178 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 A306178 Hugo Pfoertner, <a href="https://www.randomwalk.de/sequences/a306178.htm">Illustration of walks of lengths <= 3</a>. %Y A306178 Cf. A266925, A037245, A306175, A151541, A306177, A306179, A306180, A306181, A306182. %K A306178 nonn,walk,more %O A306178 1,2 %A A306178 _Hugo Pfoertner_, Jun 23 2018 %E A306178 a(7)-a(15) from _Bert Dobbelaere_, May 15 2025