%I #4 Jan 25 2013 11:45:40

%S 0,0,1,16,173,1325,15936,187794,2167196,25071259,290320330,3362811279,

%T 38954814644,451260930462,5227519694115,60556885619049,

%U 701505602257606,8126407466223744,94138215587957627,1090519135777805628

%N Number of 4Xn arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without 2-loops or left turns

%C Row 4 of A221787

%H R. H. Hardin, <a href="/A221789/b221789.txt">Table of n, a(n) for n = 1..28</a>

%e All solutions for n=3

%e ..0..2..1

%e ..1..2..0

%e ..0..2..1

%e ..1..2..0

%K nonn

%O 1,4

%A _R. H. Hardin_ Jan 25 2013