login
Squares visited by a knight on a spirally numbered board and moving to the lowest available unvisited square at each step and if no unvisited squares are available move one step back.
11

%I #17 Nov 06 2019 23:54:14

%S 1,10,3,6,9,4,7,2,5,8,11,14,29,32,15,12,27,24,45,20,23,44,41,18,35,38,

%T 19,16,33,30,53,26,47,22,43,70,21,40,17,34,13,28,25,46,75,42,69,104,

%U 37,62,95,58,55,86,51,48,77,114,73,108,151,68,103,64,67,36,39,66,63

%N Squares visited by a knight on a spirally numbered board and moving to the lowest available unvisited square at each step and if no unvisited squares are available move one step back.

%C This is an infinite extension of A316667 with which it agrees for the first 2016 terms. - _N. J. A. Sloane_, Jan 28 2019

%H Daniël Karssen, <a href="/A323808/b323808.txt">Table of n, a(n) for n = 1..100000</a>

%H M. F. Hasler, <a href="/wiki/Knight_tours">Knight tours</a>, OEIS wiki, Nov. 2019.

%H Daniël Karssen, <a href="/A323808/a323808.svg">Figure showing the first 1e5 steps of the sequence</a>

%F a(n) = A323809(n-1) + 1. - _M. F. Hasler_, Nov 06 2019

%e The board is numbered with the square spiral:

%e 17--16--15--14--13 :

%e | | :

%e 18 5---4---3 12 29

%e | | | | |

%e 19 6 1---2 11 28

%e | | | |

%e 20 7---8---9--10 27

%e | |

%e 21--22--23--24--25--26

%e See A323809 for examples where "backtracking" happens. - _M. F. Hasler_, Nov 06 2019

%o (PARI) A323808(n)=A323809(n-1)+1 \\ _M. F. Hasler_, Nov 06 2019

%Y The sequences involved in this set of related sequences are A316588, A316328, A316334, A316667, A323808, A323809, A323810, and A323811.

%Y Cf. A326924 & A326922 (using L2-norm), A328908 & A328928 (L1-norm), A328909 & A328929 (sup norm); A326916 & A326918 (digits on spiral), A326413 and A328698 (variants with other tie breaker).

%K nonn,walk

%O 1,2

%A _Daniël Karssen_, Jan 28 2019