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 A206112 Number of (n+1) X 3 0..3 arrays with every 2 X 3 or 3 X 2 subblock having exactly two counterclockwise and two clockwise edge increases. 1

%I

%S 1140,5228,22624,111552,588840,3048096,16072760,84203240,442219464,

%T 2322616208,12190484896,64028249688,336134793648,1765105097640,

%U 9267826715912,48663053519336,255518422362912,1341650195416352

%N Number of (n+1) X 3 0..3 arrays with every 2 X 3 or 3 X 2 subblock having exactly two counterclockwise and two clockwise edge increases.

%C Column 2 of A206118.

%H R. H. Hardin, <a href="/A206112/b206112.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) + 19*a(n-2) + 6*a(n-3) - 90*a(n-4) + 19*a(n-5) + 45*a(n-6) for n>8.

%F Empirical g.f.: 4*x*(285 + 737*x - 2373*x^2 - 9967*x^3 + 1778*x^4 + 16011*x^5 + 1206*x^6 - 3645*x^7) / ((1 - x)*(1 - x - x^2)*(1 - 19*x^2 - 45*x^3)). - _Colin Barker_, Jun 13 2018

%e Some solutions for n=4:

%e ..2..3..2....0..1..1....1..0..0....0..3..2....2..0..0....3..1..2....2..3..2

%e ..3..2..2....0..2..3....0..0..3....3..2..2....1..2..2....1..1..2....2..3..3

%e ..2..2..1....0..1..3....1..1..0....2..2..3....2..2..1....1..3..0....0..1..1

%e ..2..0..2....0..2..3....2..1..1....1..1..2....0..0..2....2..0..0....1..1..2

%e ..0..2..2....0..1..3....3..2..1....2..1..1....1..0..0....0..0..1....2..2..3

%Y Cf. A206118.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 03 2012

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Last modified January 22 04:27 EST 2020. Contains 331133 sequences. (Running on oeis4.)