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.

1, 4, 15, 86, 492, 2992

Offset

1,2

Comments

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.

Links

Table of n, a(n) for n=1..6.

Contest Organizers, Al Zimmermann's Programming Contests - Snakes on a Plane, Fall 2006.

Hugo Pfoertner, Illustration of walks of lengths <= 3.

Crossrefs

Cf. A266925, A037245, A306175, A151541, A306177, A306179, A306180, A306181, A306182.

Sequence in context: A237627 A034496 A079155 * A304920 A076900 A346941

Adjacent sequences: A306175 A306176 A306177 * A306179 A306180 A306181

Keyword

nonn,walk,more

Author

Hugo Pfoertner, Jun 23 2018

Status

approved