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%I #9 Jun 13 2018 05:47:17
%S 26,92,330,1184,4250,15252,54738,196448,705026,2530252,9080754,
%T 32589688,116960298,419755820,1506450938,5406463248,19403117738,
%U 69635353188,249912538754,896904721104,3218878423314,11552150479772,41459217515106
%N Number of (n+1) X 2 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to two, and every 2 X 2 determinant nonzero.
%C Column 1 of A205998.
%H R. H. Hardin, <a href="/A205991/b205991.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 2*a(n-1) + 5*a(n-2) + 3*a(n-3) - 2*a(n-4) + a(n-5).
%F Empirical g.f.: 2*x*(13 + 20*x + 8*x^2 - 7*x^3 + 4*x^4) / (1 - 2*x - 5*x^2 - 3*x^3 + 2*x^4 - x^5). - _Colin Barker_, Jun 13 2018
%e Some solutions for n=4:
%e ..1..0....1..2....2..2....1..1....2..0....2..0....2..1....1..2....2..0....0..1
%e ..2..1....1..0....1..0....0..2....1..2....1..2....0..2....0..1....0..1....2..2
%e ..1..2....2..1....2..1....1..0....0..1....1..0....1..0....2..2....2..2....1..0
%e ..2..1....0..2....1..2....2..1....1..2....0..1....2..1....1..0....1..0....2..1
%e ..1..2....2..1....0..2....0..2....1..0....1..0....1..0....2..1....0..2....0..2
%Y Cf. A205998.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 02 2012
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