%I #8 May 05 2021 10:00:07
%S 0,289,212,427716,4984812,1026177156,30374196832,3043294206016,
%T 133567666236732,10038761087929924,525060302368983108,
%U 34891927404610766400,1974298747702764055248,124298442666315631470276
%N Number of 4 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with no occupancy greater than 2.
%C Row 4 of A221200.
%H R. H. Hardin, <a href="/A221203/b221203.txt">Table of n, a(n) for n = 1..15</a>
%e Some solutions for n=3
%e ..1..2..0....0..2..2....0..2..2....0..2..0....0..2..0....0..2..1....0..2..1
%e ..0..2..0....0..2..1....0..2..0....1..2..1....2..2..1....2..2..0....0..2..1
%e ..0..2..2....0..2..1....0..2..1....2..2..0....0..2..0....0..2..0....1..2..0
%e ..1..2..0....0..2..0....1..2..0....0..2..0....1..2..0....1..2..0....0..2..1
%Y Cf. A221200.
%K nonn
%O 1,2
%A _R. H. Hardin_ Jan 04 2013