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A208009 Number of n X 4 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 0 1 1 vertically.

%I A208009 #8 Jun 26 2018 12:35:37
%S A208009 9,81,261,841,1943,4489,8643,16641,28509,48841,77129,121801,181131,
%T A208009 269361,382503,543169,743633,1018081,1353069,1798281,2331999,3024121,
%U A208009 3841451,4879681,6090213,7601049,9343473,11485321,13932179,16900321
%N A208009 Number of n X 4 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 0 1 1 vertically.
%C A208009 Column 4 of A208013.
%H A208009 R. H. Hardin, <a href="/A208009/b208009.txt">Table of n, a(n) for n = 1..210</a>
%F A208009 Empirical: a(n) = 2*a(n-1) + 4*a(n-2) - 10*a(n-3) - 5*a(n-4) + 20*a(n-5) - 20*a(n-7) + 5*a(n-8) + 10*a(n-9) - 4*a(n-10) - 2*a(n-11) + a(n-12).
%F A208009 Empirical g.f.: x*(9 + 63*x + 63*x^2 + 85*x^3 + 72*x^4 + 74*x^5 - 12*x^6 - 6*x^7 + 15*x^8 - x^9 - 3*x^10 + x^11) / ((1 - x)^7*(1 + x)^5). - _Colin Barker_, Jun 26 2018
%e A208009 Some solutions for n=4:
%e A208009 ..1..0..0..1....1..1..0..0....0..1..0..0....1..0..0..1....0..1..0..0
%e A208009 ..1..0..0..1....0..0..1..0....0..1..0..0....0..1..1..0....1..1..1..0
%e A208009 ..1..0..0..1....0..1..0..0....0..1..0..0....1..0..0..1....0..1..0..0
%e A208009 ..1..0..0..1....0..0..1..0....0..1..0..0....0..1..1..0....0..0..1..0
%Y A208009 Cf. A208013.
%K A208009 nonn
%O A208009 1,1
%A A208009 _R. H. Hardin_, Feb 22 2012