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%I #9 Jun 17 2018 05:51:32
%S 81,549,3399,19797,111495,614367,3337695,17958813,95989473,510679479,
%T 2707979133,14326037895,75662455155,399129270627,2103642300213,
%U 11080520280189,58338276097647,307048060430277,1615687942238055
%N Number of (n+1) X 2 0..2 arrays with the number of clockwise edge increases in 2 X 2 subblocks nondecreasing rightwards and downwards.
%C Column 1 of A206512.
%H R. H. Hardin, <a href="/A206505/b206505.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 9*a(n-1) - 18*a(n-2) - 15*a(n-3) + 36*a(n-4) - 20*a(n-5) + 11*a(n-6) - 2*a(n-7).
%F Empirical g.f.: 3*x*(27 - 60*x - 28*x^2 + 101*x^3 - 59*x^4 + 33*x^5 - 6*x^6) / ((1 - x)*(1 - 4*x + x^2 - x^3)*(1 - 4*x - 7*x^2 + 2*x^3)). - _Colin Barker_, Jun 17 2018
%e Some solutions for n=4:
%e ..2..2....1..2....1..2....1..2....2..2....2..1....2..1....0..0....1..2....2..0
%e ..1..0....1..2....0..1....1..2....2..1....2..0....0..2....2..1....2..2....2..2
%e ..0..1....2..0....2..2....1..0....2..1....0..1....1..0....0..2....1..2....0..2
%e ..1..2....0..1....1..0....2..1....1..1....0..2....2..1....2..0....1..0....2..0
%e ..0..2....2..2....2..1....1..2....2..1....1..0....1..2....2..1....2..1....1..2
%Y Cf. A206512.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 08 2012
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