A251484 - OEIS

%I #9 Nov 29 2018 16:29:20

%S 236,3456,50576,740096,10830016,158478336,2319053056,33935282176,

%T 496583453696,7266629615616,106334404775936,1556017884102656,

%U 22769598050123776,333193211119927296,4875699416916361216

%N Number of (n+1) X (1+1) 0..3 arrays with no 2 X 2 subblock having the sum of its diagonal elements less than the minimum of its antidiagonal elements.

%H R. H. Hardin, <a href="/A251484/b251484.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 16*a(n-1) - 20*a(n-2).

%F Empirical g.f.: 4*x*(59 - 80*x) / (1 - 16*x + 20*x^2). - _Colin Barker_, Nov 29 2018

%e Some solutions for n=3:

%e ..0..1....2..1....1..1....1..3....2..2....2..0....1..3....0..0....1..3....0..2

%e ..3..2....2..0....2..1....2..2....3..1....1..2....1..1....0..1....1..1....1..1

%e ..0..2....2..0....1..3....1..1....0..0....0..0....0..3....1..3....1..3....0..1

%e ..0..1....1..1....3..3....0..0....2..2....2..0....0..3....0..0....1..1....3..2

%Y Column 1 of A251491.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 03 2014