cp's OEIS Frontend

A308312 a(n) is the last square visited by knight moves on a spirally numbered (2n-1) X (2n-1) board, moving to the lowest available unvisited square at each step.

%I A308312 #19 Jul 23 2019 21:10:03
%S A308312 1,1,14,30,69,108,150,205,264,333,408,475,553,659,763,881,1004,1134,
%T A308312 1274,1418,1641,1811,1986,2167,2358,2557,2633,2978,2084,2084,2084,
%U A308312 2084,2084,2084,2084,2084,2084,2084,2084,2084,2084,2084,2084,2084,2084,2084,2084
%N A308312 a(n) is the last square visited by knight moves on a spirally numbered (2n-1) X (2n-1) board, moving to the lowest available unvisited square at each step.
%C A308312 A 5 X 5 board, for example, is numbered with the square spiral:
%C A308312 .
%C A308312   21--22--23--24--25
%C A308312    |
%C A308312   20   7---8---9--10
%C A308312    |   |           |
%C A308312   19   6   1---2  11
%C A308312    |   |       |   |
%C A308312   18   5---4---3  12
%C A308312    |               |
%C A308312   17--16--15--14--13
%C A308312 .
%C A308312 a(n) stays constant at 2084 for (2n-1) >= 57 since 2084 is also the last square visited by knight moves on a spirally numbered doubly infinite board, moving to the lowest available unvisited square at each step.
%Y A308312 Cf. A316667.
%K A308312 nonn
%O A308312 1,3
%A A308312 _Sangeet Paul_, May 19 2019