A251262 - OEIS

%I #7 Nov 27 2018 11:37:20

%S 26,114,480,2058,8812,37772,161906,694042,2975162,12753740,54671978,

%T 234364684,1004661088,4306723662,18461816670,79141059954,339257370296,

%U 1454309095546,6234249070708,26724622430876,114561583275826

%N Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having x11-x00 less than x10-x01.

%H R. H. Hardin, <a href="/A251262/b251262.txt">Table of n, a(n) for n = 1..210</a>

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

%F Empirical g.f.: 2*x*(13 - 8*x - 19*x^2 + 8*x^3) / (1 - 5*x + 2*x^2 + 5*x^3 - 2*x^4). - _Colin Barker_, Nov 27 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Column 2 of A251268.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 01 2014