A235653 - OEIS

%I #8 Mar 19 2018 11:58:40

%S 16,52,160,476,1392,4020,11520,32828,93200,263892,745824,2105116,

%T 5936304,16729076,47122368,132690428,373551952,1051454740,2959233056,

%U 8327823580,23434631152,65942655540,185550334592,522092927932,1469018657424

%N Number of (n+1) X (1+1) 0..1 arrays with the difference of the upper median and minimum value of each 2 X 2 subblock in lexicographically nondecreasing order rowwise and columnwise.

%C Column 1 of A235660.

%H R. H. Hardin, <a href="/A235653/b235653.txt">Table of n, a(n) for n = 1..210</a>

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

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

%e Some solutions for n=5:

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

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

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

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

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

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

%Y Cf. A235660.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 13 2014