A236271 - OEIS

%I #8 Oct 21 2018 13:45:30

%S 42,208,1048,5328,27168,138720,708640,3620768,18501536,94542752,

%T 483118496,2468772768,12615641504,64467060640,329432556960,

%U 1683430581152,8602485031328,43959490084768,224637040795040,1147915959163808

%N Number of (n+1) X (1+1) 0..2 arrays with the upper median unequal to the lower median in every 2 X 2 subblock.

%H R. H. Hardin, <a href="/A236271/b236271.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-1) + 4*a(n-2) - 16*a(n-3) - 8*a(n-4).

%F Empirical g.f.: 2*x*(21 - x - 80*x^2 - 36*x^3) / ((1 - 2*x)*(1 - 3*x - 10*x^2 - 4*x^3)). - _Colin Barker_, Oct 21 2018

%e Some solutions for n=5:

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

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

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

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

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

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

%Y Column 1 of A236278.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 21 2014