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A206866 Number of n X 3 0..1 arrays avoiding 0 0 0 horizontally and 1 0 1 vertically.

%I A206866 #11 Jun 17 2018 14:36:44
%S A206866 7,49,211,889,3967,17737,78799,350017,1555843,6915889,30739447,
%T A206866 136629265,607288711,2699272273,11997693379,53327205481,237028156975,
%U A206866 1053540057337,4682762813455,20813890672513,92513343672307,411202253906785
%N A206866 Number of n X 3 0..1 arrays avoiding 0 0 0 horizontally and 1 0 1 vertically.
%C A206866 Column 3 of A206871.
%H A206866 R. H. Hardin, <a href="/A206866/b206866.txt">Table of n, a(n) for n = 1..210</a>
%F A206866 Empirical: a(n) = 4*a(n-1) + 8*a(n-3) + 4*a(n-4) - 2*a(n-5) - a(n-6).
%F A206866 Empirical g.f.: x*(7 + 21*x + 15*x^2 - 11*x^3 - 9*x^4 - x^5) / (1 - 4*x - 8*x^3 - 4*x^4 + 2*x^5 + x^6). - _Colin Barker_, Jun 17 2018
%e A206866 Some solutions for n=4:
%e A206866   0 1 0    1 1 1    0 1 1    1 1 0    0 1 0    0 1 1    0 0 1
%e A206866   1 0 1    1 1 0    1 1 0    0 0 1    1 0 0    0 1 1    0 0 1
%e A206866   0 0 1    1 0 0    1 1 0    0 0 1    1 0 1    0 1 1    1 1 1
%e A206866   0 1 0    1 0 1    1 0 1    1 0 0    1 1 0    0 1 1    0 0 1
%Y A206866 Cf. A206871.
%K A206866 nonn
%O A206866 1,1
%A A206866 _R. H. Hardin_, Feb 13 2012