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%I
%S 562,13098,295448,6711168,152153160,3452051294,78298719958,
%T 1776153151954,40289004709802,913904480044196,20730591242525088,
%U 470244787257936734,10666837893533545782,241962270764619764754,5488573721848784927246
%N Half the number of (n+1)X3 0..3 arrays with every 2X2 subblock having two or four distinct clockwise edge differences
%C Column 2 of A209913
%H R. H. Hardin, <a href="/A209907/b209907.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 16*a(n-1) +227*a(n-2) -1440*a(n-3) -8244*a(n-4) +46409*a(n-5) +53926*a(n-6) -406100*a(n-7) -117231*a(n-8) +1484559*a(n-9) +166049*a(n-10) -2587430*a(n-11) -386782*a(n-12) +2096907*a(n-13) +472125*a(n-14) -660956*a(n-15) -166954*a(n-16) +44616*a(n-17) +4488*a(n-18) -192*a(n-19)
%e Some solutions for n=4
%e ..3..0..1....3..0..0....2..2..1....1..2..3....3..0..1....3..3..1....1..1..3
%e ..2..0..3....1..1..3....3..0..2....2..3..1....1..3..0....1..0..3....0..3..0
%e ..1..2..0....3..0..3....0..3..3....1..2..3....2..1..1....2..3..0....0..1..0
%e ..2..0..3....2..0..1....1..0..2....3..1..2....1..3..0....1..2..1....0..3..1
%e ..0..2..0....2..3..1....1..3..2....3..0..3....3..0..1....2..1..2....3..0..0
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 15 2012
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