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%I #4 Jan 07 2013 16:49:20
%S 0,7,112,1648,22914,311988,4202440,56306491,752377824,10039480767,
%T 133868165460,1784368349249,23779898954002,316879002290160,
%U 4222360270783970,56260809604666184,749636868848349394
%N Number of nX3 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 3 of A217227
%H R. H. Hardin, <a href="/A217223/b217223.txt">Table of n, a(n) for n = 1..18</a>
%e Some solutions for n=3
%e ..1..1..0....1..1..0....1..1..0....1..2..1....1..2..1....0..1..0....1..2..1
%e ..2..1..0....2..2..0....1..1..2....1..1..1....1..1..2....1..2..2....2..1..1
%e ..1..2..1....1..2..0....1..1..1....1..1..0....0..0..1....1..1..1....1..0..0
%K nonn
%O 1,2
%A _R. H. Hardin_ Jan 07 2013
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