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A207840 Number of n X 3 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 0 and 1 1 1 vertically.

%I A207840 #8 Feb 21 2018 07:00:04
%S A207840 6,36,72,240,704,2080,6216,18496,55000,163760,487296,1450192,4315896,
%T A207840 12844160,38224536,113757504,338545344,1007520656,2998410360,
%U A207840 8923354336,26556156776,79031879392,235201123584,699965244000,2083116504872
%N A207840 Number of n X 3 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 0 and 1 1 1 vertically.
%C A207840 Column 3 of A207845.
%H A207840 R. H. Hardin, <a href="/A207840/b207840.txt">Table of n, a(n) for n = 1..210</a>
%F A207840 Empirical: a(n) = a(n-1) + 4*a(n-2) + 5*a(n-3) + 2*a(n-4) - a(n-5) + a(n-6) for n>8.
%F A207840 Empirical g.f.: 2*x*(3 + 15*x + 6*x^2 - 3*x^3 - 8*x^4 - 5*x^5 + 3*x^6 - 2*x^7) / (1 - x - 4*x^2 - 5*x^3 - 2*x^4 + x^5 - x^6). - _Colin Barker_, Feb 21 2018
%e A207840 Some solutions for n=4:
%e A207840 ..1..1..1....0..1..1....1..1..0....1..1..0....1..0..1....0..1..0....0..1..1
%e A207840 ..1..0..1....1..0..1....1..0..1....1..0..0....1..0..0....0..1..0....1..0..0
%e A207840 ..0..1..0....0..1..0....0..1..1....0..1..1....0..1..0....1..0..1....1..0..1
%e A207840 ..0..1..1....1..1..1....0..1..0....1..1..0....1..0..1....0..1..1....0..1..0
%Y A207840 Cf. A207845.
%K A207840 nonn
%O A207840 1,1
%A A207840 _R. H. Hardin_, Feb 21 2012