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A207509 Number of n X 3 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 1 1 vertically.

%I A207509 #8 Mar 05 2018 09:10:48
%S A207509 6,36,72,166,360,660,1292,2400,4396,8096,14580,26346,47336,84502,
%T A207509 150976,268594,477130,846850,1500112,2655880,4697786,8303004,14669200,
%U A207509 25901790,45719422,80675866,142317030,251007562,442623618,780396916,1375769956
%N A207509 Number of n X 3 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 1 1 vertically.
%C A207509 Column 3 of A207514.
%H A207509 R. H. Hardin, <a href="/A207509/b207509.txt">Table of n, a(n) for n = 1..210</a>
%F A207509 Empirical: a(n) = 2*a(n-1) + 2*a(n-3) - 5*a(n-4) + a(n-5) - 4*a(n-6) + 5*a(n-7) - a(n-8) + 2*a(n-9) - a(n-10) for n>11.
%F A207509 Empirical g.f.: 2*x*(3 + 12*x + 5*x^3 - 7*x^4 - 15*x^5 - 6*x^6 - 16*x^7 + 12*x^8 - 6*x^9 + 2*x^10) / ((1 - x)*(1 - x - x^3)*(1 - x^2 - 3*x^3 - x^4 - x^5 + x^6)). - _Colin Barker_, Mar 05 2018
%e A207509 Some solutions for n=4:
%e A207509 ..0..1..0....0..1..0....0..0..1....0..0..1....0..0..1....1..1..1....1..1..0
%e A207509 ..1..1..1....0..0..1....1..0..0....1..0..1....1..0..0....1..1..0....1..1..1
%e A207509 ..1..0..0....0..1..0....0..0..1....1..0..0....1..0..1....0..0..1....0..0..1
%e A207509 ..0..0..1....0..1..0....1..0..0....0..0..1....0..0..1....1..1..1....1..1..0
%Y A207509 Cf. A207514.
%K A207509 nonn
%O A207509 1,1
%A A207509 _R. H. Hardin_, Feb 18 2012