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A233021 Number of n X 3 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally, vertically, diagonally or antidiagonally, and top left element zero.

%I A233021 #8 Oct 07 2018 08:36:50
%S A233021 9,81,849,8835,92067,959385,9997413,104179551,1085618895,11312857317,
%T A233021 117887355777,1228463178219,12801387988827,133398816787089,
%U A233021 1390102724464989,14485777543658775,150951255149241255
%N A233021 Number of n X 3 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally, vertically, diagonally or antidiagonally, and top left element zero.
%H A233021 R. H. Hardin, <a href="/A233021/b233021.txt">Table of n, a(n) for n = 1..210</a>
%F A233021 Empirical: a(n) = 11*a(n-1) - 5*a(n-2) - 11*a(n-3) + 2*a(n-4).
%F A233021 Empirical g.f.: 3*x*(3 - 6*x + x^2) / (1 - 11*x + 5*x^2 + 11*x^3 - 2*x^4). - _Colin Barker_, Oct 07 2018
%e A233021 Some solutions for n=5:
%e A233021 ..0..1..0....0..0..1....0..0..0....0..1..0....0..1..3....0..0..0....0..1..0
%e A233021 ..0..1..1....1..1..1....2..2..2....1..1..0....0..1..1....0..2..0....0..1..1
%e A233021 ..0..1..0....3..3..3....3..2..0....1..0..0....1..1..1....2..0..2....1..1..1
%e A233021 ..1..1..1....1..1..1....3..2..2....0..0..0....1..3..3....2..0..2....1..3..3
%e A233021 ..1..0..0....3..3..1....2..2..2....0..0..2....1..1..1....2..2..2....3..3..2
%Y A233021 Column 3 of A233026.
%K A233021 nonn
%O A233021 1,1
%A A233021 _R. H. Hardin_, Dec 03 2013