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A207026 Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 0 1 vertically.

%I A207026 #7 Jul 22 2025 19:57:32
%S A207026 6,36,90,252,624,1350,3025,6256,12788,25792,50630,99012,190920,365041,
%T A207026 694038,1309524,2460150,4599952,8565768,15899422,29415965,54278252,
%U A207026 99908040,183482116,336298170,615243752,1123669472,2049072321,3731220822
%N A207026 Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 0 1 vertically.
%C A207026 Row 3 of A207024
%H A207026 R. H. Hardin, <a href="/A207026/b207026.txt">Table of n, a(n) for n = 1..210</a>
%F A207026 Empirical: a(n) = 3*a(n-1) +a(n-2) -5*a(n-3) -10*a(n-4) +12*a(n-5) +11*a(n-6) +a(n-7) -15*a(n-8) +a(n-9) -7*a(n-10) +3*a(n-11) +3*a(n-12) +9*a(n-13) -4*a(n-14) -2*a(n-16) -a(n-18) +a(n-19)
%e A207026 Some solutions for n=4
%e A207026 ..1..0..0..1....0..1..0..1....0..0..1..0....1..1..1..0....1..1..0..0
%e A207026 ..0..1..0..0....0..1..0..1....1..0..1..0....0..0..1..0....1..1..1..1
%e A207026 ..0..1..0..0....0..1..0..1....0..0..1..0....0..0..1..0....1..1..0..0
%K A207026 nonn
%O A207026 1,1
%A A207026 _R. H. Hardin_ Feb 14 2012