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A207249 Number of n X 3 0..1 arrays avoiding 0 0 1 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.

%I A207249 #8 Feb 20 2018 14:26:44
%S A207249 6,36,102,370,1232,4238,14406,49164,167530,571202,1947168,6638170,
%T A207249 22629802,77146700,262997994,896578158,3056494736,10419796218,
%U A207249 35521783770,121096145300,412824884294,1407347734502,4797742864320
%N A207249 Number of n X 3 0..1 arrays avoiding 0 0 1 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.
%C A207249 Column 3 of A207254.
%H A207249 R. H. Hardin, <a href="/A207249/b207249.txt">Table of n, a(n) for n = 1..210</a>
%F A207249 Empirical: a(n) = 2*a(n-1) + 4*a(n-2) + 7*a(n-4) + 8*a(n-5) - a(n-8).
%F A207249 Empirical g.f.: 2*x*(3 + 12*x + 3*x^2 + 11*x^3 + 21*x^4 - 3*x^5 - 3*x^7) / (1 - 2*x - 4*x^2 - 7*x^4 - 8*x^5 + x^8). - _Colin Barker_, Feb 20 2018
%e A207249 Some solutions for n=4:
%e A207249 ..0..0..0....1..0..0....0..1..0....1..1..0....1..0..0....1..1..0....0..0..0
%e A207249 ..0..1..1....0..0..0....1..0..0....1..0..0....1..0..0....0..0..0....1..0..0
%e A207249 ..1..1..1....0..0..0....1..0..0....1..0..0....1..0..0....0..0..0....1..1..1
%e A207249 ..1..0..0....0..1..0....1..1..0....0..1..1....1..0..0....1..0..0....0..1..1
%Y A207249 Cf. A207254.
%K A207249 nonn
%O A207249 1,1
%A A207249 _R. H. Hardin_, Feb 16 2012