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%I #8 Oct 11 2018 11:23:57
%S 40,148,556,2104,7976,30260,114820,435720,1653488,6274804,23812172,
%T 90364680,342924296,1301361476,4938528804,18741194360,71120848176,
%U 269896091748,1024227097996,3886833426776,14750121431720,55975149559572
%N Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock having the sum of the absolute values of the edge differences equal to 6 and no adjacent elements equal.
%H R. H. Hardin, <a href="/A233726/b233726.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 3*a(n-1) + 5*a(n-2) - 7*a(n-3) - 2*a(n-4).
%F Empirical g.f.: 4*x*(10 + 7*x - 22*x^2 - 6*x^3) / (1 - 3*x - 5*x^2 + 7*x^3 + 2*x^4). - _Colin Barker_, Oct 11 2018
%e Some solutions for n=5:
%e ..0..2....3..1....3..2....0..2....2..3....0..1....0..1....1..3....0..2....3..0
%e ..2..1....2..0....2..0....1..3....1..0....1..3....1..3....0..2....1..3....2..1
%e ..0..2....1..2....0..1....0..1....0..2....2..1....0..1....2..1....3..2....3..0
%e ..2..3....0..3....2..3....3..2....2..1....0..2....2..0....1..3....0..1....2..1
%e ..1..0....1..2....3..1....0..1....0..2....2..1....0..1....0..2....2..0....0..2
%e ..3..2....2..0....1..0....1..3....1..0....1..3....1..3....1..3....0..1....2..1
%Y Column 1 of A233733.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 15 2013
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