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%I #8 Dec 26 2018 11:51:55
%S 20,22,42,62,101,152,265,382,652,962,1649,2412,4135,6062,10386,15222,
%T 26089,38232,65517,96022,164556,241162,413285,605692,1037987,1521222,
%U 2606954,3820622,6547485,9595672,16444321,24099982,41300684,60528242
%N Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 or 01010101.
%H R. H. Hardin, <a href="/A259735/b259735.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-2) + 3*a(n-4) + 2*a(n-6) for n>7.
%F Empirical g.f.: x*(20 + 22*x + 22*x^2 + 40*x^3 - x^4 + 24*x^5 - 2*x^6) / (1 - x^2 - 3*x^4 - 2*x^6). - _Colin Barker_, Dec 26 2018
%e Some solutions for n=4:
%e ..0..1..0....0..1..0....0..0..1....1..0..0....1..0..1....0..1..0....0..1..0
%e ..1..0..1....1..0..1....0..0..0....0..1..0....0..1..0....1..0..1....1..0..0
%e ..0..1..0....0..1..0....1..0..1....1..0..1....1..0..1....0..0..0....0..1..0
%e ..1..0..1....0..0..1....0..1..0....0..1..0....0..0..0....1..0..1....1..0..1
%e ..0..0..0....0..1..0....1..0..1....1..0..0....1..0..1....0..1..0....0..1..0
%e ..1..0..1....1..0..1....0..0..0....0..1..0....0..1..0....0..0..1....0..0..1
%Y Column 1 of A259742.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jul 04 2015
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