A227439 - OEIS

%I #6 Apr 05 2020 22:21:58

%S 8,62,457,3346,24568,180575,1327102,9752326,71665377,526639966,

%T 3870071062,28439626805,208991567034,1535796359850,11285960160481,

%U 82936058669080,609464300937756,4478712154302465,32912284659166926

%N Number of n X 3 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X 4 binary array having two adjacent 1's and two adjacent 0's.

%C Column 3 of A227442.

%H R. H. Hardin, <a href="/A227439/b227439.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 11*a(n-1) -36*a(n-2) +79*a(n-3) -87*a(n-4) -7*a(n-5) +159*a(n-6) -206*a(n-7) +127*a(n-8) -31*a(n-9).

%e Some solutions for n=4

%e ..1..0..0....1..1..1....1..1..1....0..0..0....1..0..0....0..0..0....0..1..0

%e ..0..0..1....0..0..0....0..0..0....0..1..1....0..1..1....0..0..1....0..0..0

%e ..0..1..0....0..1..1....0..0..1....0..1..1....1..0..0....0..0..0....1..1..1

%e ..0..1..1....0..0..0....0..0..0....1..1..1....1..0..1....1..1..0....1..1..1

%K nonn

%O 1,1

%A _R. H. Hardin_ Jul 11 2013