A209890 - OEIS

%I #12 Oct 10 2014 13:27:18

%S 7,34,164,792,3824,18464,89152,430464,2078464,10035712,48456704,

%T 233969664,1129705472,5454700544,26337624064,127169298432,

%U 614027689984,2964787953664,14315262574592,69120202113024,333741858750464

%N Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock having two distinct values, and new values 0..2 introduced in row major order.

%C Column 1 of A209897.

%H R. H. Hardin, <a href="/A209890/b209890.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) +4*a(n-2).

%F Empirical G.f.: x*(7+6*x)/(1-4*x-4*x^2). [_Colin Barker_, Mar 15 2012]

%e Some solutions for n=4:

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

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

%e ..1..0....2..0....0..0....0..1....1..0....1..0....1..0....1..0....1..0....2..2

%e ..0..0....0..0....2..0....1..0....0..1....0..0....0..0....1..0....0..0....2..0

%e ..2..2....2..2....0..0....1..1....0..0....2..2....0..2....0..1....1..0....2..2

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 14 2012