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A231264 Number of (2+1) X (n+1) 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with values 0..2 introduced in row major order.

%I A231264 #8 Feb 16 2018 09:38:12
%S A231264 6,15,32,83,211,557,1471,3909,10387,27617,73419,195197,518979,1379897,
%T A231264 3669051,9755861,25940515,68974961,183402043,487659661,1296670403,
%U A231264 3447803113,9167594299,24376331077,64815862051,172343243361,458255009275
%N A231264 Number of (2+1) X (n+1) 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with values 0..2 introduced in row major order.
%C A231264 Row 2 of A231263.
%H A231264 R. H. Hardin, <a href="/A231264/b231264.txt">Table of n, a(n) for n = 1..210</a>
%F A231264 Empirical: a(n) = 4*a(n-1) -2*a(n-2) -8*a(n-3) +11*a(n-4) -4*a(n-6) -4*a(n-7) -4*a(n-8) +8*a(n-9).
%F A231264 Empirical g.f.: x*(6 - 9*x - 16*x^2 + 33*x^3 - 3*x^4 - 30*x^5 + x^6 - 2*x^7 + 40*x^8) / ((1 - x)*(1 + x)*(1 - 2*x + 2*x^2)*(1 - 2*x^2)*(1 - 2*x - x^2 - 2*x^3)). - _Colin Barker_, Feb 16 2018
%e A231264 Some solutions for n=3:
%e A231264 ..0..0..0..0....0..0..0..1....0..0..0..0....0..0..0..0....0..0..0..0
%e A231264 ..0..0..1..1....0..0..1..1....1..1..2..2....0..0..0..0....1..1..1..0
%e A231264 ..1..1..1..1....0..1..1..1....1..2..2..2....1..1..1..1....1..1..0..0
%K A231264 nonn
%O A231264 1,1
%A A231264 _R. H. Hardin_, Nov 06 2013