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A207177 Number of n X 3 0..1 arrays avoiding 0 0 0 horizontally and 0 1 0 vertically.

%I A207177 #8 Jun 21 2018 05:49:36
%S A207177 7,49,241,1171,5917,30067,151981,767377,3877045,19592047,98998267,
%T A207177 500220187,2527540111,12771357967,64532102977,326072549563,
%U A207177 1647603384079,8325132536305,42065847045655,212553428463613,1074005709153595
%N A207177 Number of n X 3 0..1 arrays avoiding 0 0 0 horizontally and 0 1 0 vertically.
%C A207177 Column 3 of A207182.
%H A207177 R. H. Hardin, <a href="/A207177/b207177.txt">Table of n, a(n) for n = 1..210</a>
%F A207177 Empirical: a(n) = 4*a(n-1) + 2*a(n-2) + 12*a(n-3) + 23*a(n-4) + 6*a(n-5) - a(n-6) - 2*a(n-7) - a(n-8).
%F A207177 Empirical g.f.: x*(7 + 21*x + 31*x^2 + 25*x^3 + 2*x^4 - 4*x^5 - 3*x^6 - x^7) / (1 - 4*x - 2*x^2 - 12*x^3 - 23*x^4 - 6*x^5 + x^6 + 2*x^7 + x^8). - _Colin Barker_, Jun 21 2018
%e A207177 Some solutions for n=4:
%e A207177 ..0..1..1....1..0..0....0..0..1....0..0..1....0..0..1....0..0..1....1..1..1
%e A207177 ..0..1..1....1..0..1....0..0..1....1..0..0....0..0..1....0..1..1....1..1..1
%e A207177 ..0..1..1....1..0..1....0..0..1....1..1..1....1..1..1....1..1..0....0..1..0
%e A207177 ..0..1..1....1..0..1....1..1..1....0..1..1....1..1..0....1..0..0....0..1..0
%Y A207177 Cf. A207182.
%K A207177 nonn
%O A207177 1,1
%A A207177 _R. H. Hardin_, Feb 15 2012