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%I #8 Dec 07 2018 11:50:01
%S 279,432,738,1296,2502,4986,9936,20052,40770,82872,168516,343062,
%T 698688,1422756,2897190,5900472,12017268,24474006,49843512,101512980,
%U 206743590,421055928,857529828,1746463734,3556879416,7244001396,14753268774
%N Number of (n+2) X (2+2) 0..2 arrays with every consecutive three elements in every row, column, diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.
%H R. H. Hardin, <a href="/A252855/b252855.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) + a(n-2) + 3*a(n-3) + a(n-4) - 3*a(n-5) - 4*a(n-6) - 2*a(n-7) + 2*a(n-8) + 2*a(n-9).
%F Empirical g.f.: 9*x*(31 + 17*x + 3*x^2 - 79*x^3 - 123*x^4 - 69*x^5 + 26*x^6 + 92*x^7 + 52*x^8) / ((1 - x)*(1 + x + x^2)*(1 - x - x^2 - 2*x^3 - 2*x^4 + 2*x^5 + 2*x^6)). - _Colin Barker_, Dec 07 2018
%e Some solutions for n=4:
%e ..0..1..0..0....0..1..0..1....0..1..0..0....0..1..1..2....0..1..0..1
%e ..2..0..0..1....1..1..0..0....2..2..0..0....2..2..1..1....0..1..1..2
%e ..2..1..1..0....0..0..1..0....2..1..2..1....2..2..0..2....1..2..1..2
%e ..0..0..1..1....1..0..0..2....1..2..2..1....1..0..0..2....1..1..0..0
%e ..0..0..2..0....0..1..1..2....1..2..1..2....1..2..2..0....2..2..0..0
%e ..1..2..2..0....1..1..0..0....0..0..2..2....2..0..2..2....2..2..1..1
%Y Column 2 of A252861.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 23 2014
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