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%I #8 Apr 12 2018 08:43:14
%S 6,19,60,190,602,1908,6048,19172,60776,192664,610760,1936160,6137792,
%T 19457328,61681408,195535392,619864096,1965022784,6229292160,
%U 19747394880,62600949632,198450424448,629105008768,1994317286912,6322158281216
%N Half the number of (n+1) X 2 binary arrays with no 2 X 2 subblock containing exactly one 1.
%C Column 1 of A184197.
%H R. H. Hardin, <a href="/A184189/b184189.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 2*a(n-3).
%F Empirical g.f.: x*(2 + x)*(3 - 4*x) / (1 - 4*x + 2*x^2 + 2*x^3). - _Colin Barker_, Apr 12 2018
%e Some solutions for 3 X 2:
%e ..1..1....1..0....0..1....0..1....0..1....1..1....0..1....1..0....1..0....0..1
%e ..0..0....0..1....1..1....1..0....0..1....1..1....0..1....1..1....1..0....1..1
%e ..0..0....0..1....0..1....0..1....1..1....0..1....1..0....0..0....0..1....1..1
%Y Cf. A184197.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 10 2011
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