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A280481 Number of 2 X n 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards. 1

%I

%S 0,6,22,63,162,381,884,1995,4478,9913,21832,47687,103666,224117,

%T 482556,1034819,2211686,4712113,10011696,21217471,44862298,94656621,

%U 199333092,419016123,879354062,1842593961,3855445784,8056377655,16813670338

%N Number of 2 X n 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

%H R. H. Hardin, <a href="/A280481/b280481.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-1) - 4*a(n-2) - 14*a(n-3) + 19*a(n-4) + 13*a(n-5) - 22*a(n-6) - 4*a(n-7) + 8*a(n-8) for n>10.

%F Empirical g.f.: x^2*(6 - 8*x - 23*x^2 + 19*x^3 + 17*x^4 + 13*x^5 + 16*x^6 - 16*x^7 - 40*x^8) / ((1 - x)^2*(1 + x)^3*(1 - 2*x)^3). - _Colin Barker_, Feb 13 2019

%e Some solutions for n=4:

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

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

%Y Row 2 of A280480.

%K nonn

%O 1,2

%A _R. H. Hardin_, Jan 04 2017

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Last modified May 17 10:16 EDT 2022. Contains 353745 sequences. (Running on oeis4.)