A306178 - OEIS

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, 18172, 110643, 672267, 4069122, 24578785, 147972210, 889332713, 5331980703, 31924424199

(list; graph; refs; listen; history; text; internal format)

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..15.

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

EXTENSIONS

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

STATUS

approved