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%I #8 Jun 26 2018 11:00:44
%S 9,81,221,536,1711,4993,16742,53411,182247,608142,2095301,7157363,
%T 24822376,85845073,299033933,1040987192,3636447903,12703622001,
%U 44454269798,155590727603,545028524023,1909557999406,6693157243061
%N Number of n X 4 0..1 arrays avoiding 0 0 1 and 1 0 0 horizontally and 0 1 1 and 1 1 0 vertically.
%C Column 4 of A208007.
%H R. H. Hardin, <a href="/A208003/b208003.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 36*a(n-3) + 54*a(n-4) + 24*a(n-5) - 69*a(n-6) + 12*a(n-7) + 19*a(n-8) - 6*a(n-9) for n>10.
%F G.f.: x*(9 + 27*x - 238*x^2 - 223*x^3 + 1588*x^4 - 299*x^5 - 2044*x^6 + 767*x^7 + 603*x^8 - 234*x^9) / ((1 - x)*(1 + x)*(1 - 3*x + x^2)*(1 - x - x^2)*(1 - 2*x - 7*x^2 + 6*x^3)). - _Colin Barker_, Jun 26 2018
%e Some solutions for n=4:
%e ..1..0..1..1....0..1..0..1....1..1..1..0....1..1..1..0....1..1..0..1
%e ..0..1..1..0....0..0..0..0....0..0..0..0....1..0..1..1....0..1..0..1
%e ..1..0..1..1....0..1..0..1....1..1..1..0....1..1..1..0....0..1..1..1
%e ..0..1..1..0....0..0..0..0....0..0..0..0....1..0..1..1....0..1..0..1
%Y Cf. A208007.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 22 2012
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