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Number of n X 3 0..2 arrays with no element equal to any value at offset (-2,-1) (-1,0) or (-1,1) and new values introduced in order 0..2.
1

%I #8 Feb 01 2019 05:32:53

%S 5,16,25,41,85,181,389,834,1781,3799,8110,17328,37032,79130,169059,

%T 361178,771648,1648657,3522441,7525825,16079113,34353402,73396957,

%U 156814715,335039190,715820740,1529371036,3267543982,6981199507

%N Number of n X 3 0..2 arrays with no element equal to any value at offset (-2,-1) (-1,0) or (-1,1) and new values introduced in order 0..2.

%H R. H. Hardin, <a href="/A275178/b275178.txt">Table of n, a(n) for n = 1..210</a>

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

%F Empirical g.f.: x*(5 - 4*x - 9*x^2 + 12*x^3 - 4*x^4 - 17*x^5 + 11*x^6 + 5*x^7) / ((1 - x)*(1 - 3*x + 3*x^2 - 2*x^3 - x^4)). - _Colin Barker_, Feb 01 2019

%e Some solutions for n=4:

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

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

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

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

%Y Column 3 of A275183.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jul 19 2016