A306181 Number of unrooted self-avoiding walks with n steps that can make turns from the set +-Pi/11, +-3*Pi/11, +-5*Pi/11, +-7*Pi/11, +-9*Pi/11.

1, 5, 28, 235, 1970, 17201, 149420, 1295637, 11178026, 96047288, 822418731, 7020762655

Offset

1,2

Comments

The turning angles are those of the regular 11-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..12.

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, A306182.

Sequence in context: A183375 A000530 A121674 * A377325 A362690 A116977

Adjacent sequences: A306178 A306179 A306180 * A306182 A306183 A306184

Keyword

nonn,walk,more

Author

Hugo Pfoertner, Jun 23 2018

Extensions

a(7)-a(12) from Bert Dobbelaere, May 15 2025

Status

approved