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%I #4 Jan 07 2013 16:50:15
%S 0,38,1648,67956,2662621,102825095,3940138931,150405053021,
%T 5729680653464,218036689302796,8292350386134653,315276121028319608,
%U 11984839981037388864,455548467001108257477,17314744679135811905542
%N Number of nX4 arrays of occupancy after each element moves to some horizontal or vertical neighbor, with no 2-loops and with no occupancy greater than 2
%C Column 4 of A217227
%H R. H. Hardin, <a href="/A217224/b217224.txt">Table of n, a(n) for n = 1..26</a>
%e Some solutions for n=3
%e ..0..0..2..1....1..2..0..0....1..0..0..0....0..0..2..1....1..2..1..0
%e ..2..2..2..2....2..1..0..1....2..2..2..2....2..1..1..2....1..2..1..2
%e ..0..0..0..1....1..1..2..1....1..1..0..1....0..1..1..1....0..1..0..1
%K nonn
%O 1,2
%A _R. H. Hardin_ Jan 07 2013