A306182 Number of unrooted self-avoiding walks with n steps that can make turns from the set 0, +-Pi/6, +-2*Pi/6, +-3*Pi/6, +-4*Pi/6, +-5*Pi/6.

1, 6, 33, 306, 2765, 26290

Offset

1,2

Comments

The turning angles are those of the regular 12-gon, 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, A306178, A306179, A306180, A306181.

Sequence in context: A228618 A118094 A343567 * A354888 A358595 A121376

Adjacent sequences: A306179 A306180 A306181 * A306183 A306184 A306185

Keyword

nonn,walk,more

Author

Hugo Pfoertner, Jun 23 2018

Status

approved