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On a spirally numbered square grid, with labels starting at 1, this is the number of steps that a (1,n) leaper makes before getting trapped, or -1 if it never gets trapped.
11

%I #9 Apr 30 2021 21:23:23

%S -1,2016,3723,13103,14570,26967,101250,158735,132688,220439,144841,

%T 646728,350720,66183,75259,248764,118694,307483,238208,189159,139639,

%U 183821,151016,171076,114187,262235,178612,257632,124475,178862,143674,196795,60707,309820

%N On a spirally numbered square grid, with labels starting at 1, this is the number of steps that a (1,n) leaper makes before getting trapped, or -1 if it never gets trapped.

%C A (1,2) leaper is a chess knight.

%C a(2)-a(5) were computed by _Daniël Karssen_.

%H Rémy Sigrist, <a href="/A323469/b323469.txt">Table of n, a(n) for n = 1..1000</a>

%H N. J. A. Sloane and Brady Haran, <a href="https://www.youtube.com/watch?v=RGQe8waGJ4w">The Trapped Knight</a>, Numberphile video (2019)

%Y The sequences involved in this set of related sequences are A316884, A316967, A316667, A316328, A317106, A317105, A317416, A317415, A317438, A317437, and A323469, A323470, A323471, A323472.

%K sign

%O 1,2

%A _N. J. A. Sloane_, Jan 28 2019

%E More terms from _Rémy Sigrist_, Jan 29 2019