%I #4 Jan 22 2013 07:15:28

%S 1,987,63676,7033429,659020617,64509677154,6233675847228,

%T 604346923784252,58538232535028520,5671250113728678882,

%U 549411330594167686392,53225495837252796349285,5156336905625087231654148

%N Number of 4Xn arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, without consecutive moves in the same direction

%C Row 4 of A221693

%H R. H. Hardin, <a href="/A221696/b221696.txt">Table of n, a(n) for n = 1..18</a>

%e Some solutions for n=3

%e ..2..0..0....2..0..1....0..1..1....1..0..0....0..4..1....1..0..0....0..3..2

%e ..0..3..1....1..1..0....2..3..0....1..4..0....0..0..1....2..2..1....0..0..1

%e ..1..0..1....2..0..0....0..0..0....2..0..2....2..1..0....0..2..0....1..2..1

%e ..1..3..0....1..3..1....2..1..2....0..1..1....0..3..0....1..3..0....1..0..1

%K nonn

%O 1,2

%A _R. H. Hardin_ Jan 22 2013