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%I #8 Mar 31 2012 12:35:51
%S 1,3,4,8,18,32,64,132,256,512,1032,2048,4096,8208,16384,32768,65568,
%T 131072,262144,524352,1048576,2097152,4194432,8388608,16777216,
%U 33554688,67108864,134217728,268435968,536870912,1073741824,2147484672,4294967296
%N Half the number of nX1 0..2 arrays with no element equal to the sum mod 3 of its horizontal and vertical neighbors
%C Column 1 of A183501
%H R. H. Hardin, <a href="/A183494/b183494.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n)=2*a(n-1)+2*a(n-3)-4*a(n-4).
%F Empirical G.f.: x*(1+x)*(1-2*x^2)/(1-2*x)/(1-2*x^3). [Colin Barker, Feb 23 2012]
%e All solutions for 3X1
%e ..0....1....0....0....0....1....2....2
%e ..2....0....1....1....2....2....1....0
%e ..1....1....2....0....0....0....0....2
%K nonn
%O 1,2
%A _R. H. Hardin_ Jan 05 2011
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