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%I #7 Dec 10 2015 02:07:26
%S 256,1776,12712,91440,656272,4711264,33827496,242859696,1743558448,
%T 12517828752,89871316488,645223555056,4632334222640,33257550378496,
%U 238770342344520,1714234994048944,12307232871040912,88358941969931504
%N Number of (n+1) X 2 0..3 arrays with no 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases in its adjacent leftward or upward neighbors.
%C Column 1 of A205944.
%H R. H. Hardin, <a href="/A205937/b205937.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 16*a(n-2) + 132*a(n-3) + 626*a(n-4) + 1504*a(n-5) + 2204*a(n-6) + 2140*a(n-7) + 1011*a(n-8) + 96*a(n-9) + 80*a(n-10).
%e Some solutions for n=4:
%e ..1..1....3..3....1..0....2..2....0..3....1..0....1..1....3..1....2..2....1..1
%e ..2..0....1..1....0..0....1..0....3..0....0..1....2..0....1..1....0..2....2..1
%e ..2..0....1..1....0..0....0..3....2..1....0..0....2..2....3..2....2..1....3..2
%e ..1..0....2..3....1..2....0..0....3..2....3..2....1..0....0..3....1..1....1..2
%e ..3..2....1..0....1..1....2..1....3..1....1..3....3..2....1..3....1..1....0..3
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 01 2012
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