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%I #12 Jun 13 2018 11:23:49
%S 81,270,972,3564,13608,52812,205416,803844,3153816,12375180,48598056,
%T 190924452,750064536,2947003884,11579514408,45498547908,178776400536,
%U 702469087308,2760220004904,10845780014052,42616578679704
%N Number of (n+1) X 2 0..2 arrays with every 2 X 3 or 3 X 2 subblock having exactly two counterclockwise and two clockwise edge increases.
%C Column 1 of A206094.
%H R. H. Hardin, <a href="/A206087/b206087.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) - a(n-2) + 12*a(n-3) - 36*a(n-4).
%F Empirical g.f.: 27*x*(3 - 2*x - x^2 - 38*x^3) / ((1 - 2*x)*(1 - 2*x - 3*x^2 - 18*x^3)). - _Colin Barker_, Jun 13 2018
%e Some solutions for n=4:
%e ..2..1....2..1....1..0....1..2....2..2....0..1....0..0....0..0....2..2....1..1
%e ..1..1....0..2....0..2....1..1....2..0....2..1....1..0....2..0....2..0....0..1
%e ..1..0....2..2....0..0....1..0....0..2....2..0....2..1....0..1....0..1....2..0
%e ..0..1....1..1....2..0....2..1....2..2....1..0....2..2....1..1....1..1....2..0
%e ..0..0....0..1....0..1....1..1....1..2....2..2....1..2....0..0....0..0....1..2
%Y Cf. A206094.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 03 2012
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