%I #9 Jul 07 2018 19:29:27
%S 0,0,1,3,4,22,69,418,2210,14024
%N Number of self-avoiding polygons with perimeter n and sides = 1 that have vertex angles from the set 0, +-Pi/6, +-*Pi/3, +-Pi/2, +-2*Pi/3, +-5*Pi/6, not counting rotations and reflections as distinct.
%C Holes are excluded, i.e., the boundary path may nowhere touch or intersect itself.
%H 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 Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/a316192.htm">Illustration of polygons of perimeter <= 8</a>.
%Y Cf. A258206, A266549, A284869, A306182, A316195, A316197, A316198, A316199, A316200, A316201.
%K nonn,walk,more
%O 1,4
%A _Hugo Pfoertner_, Jul 07 2018