A251311 - OEIS

%I #8 Nov 28 2018 10:57:48

%S 25,79,238,720,2199,6717,20484,62464,190542,581259,1773061,5408458,

%T 16497878,50325018,153510819,468267241,1428396280,4357161996,

%U 13291031298,40542790911,123671208989,377245070870,1150743527834,3510213300150

%N Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having the maximum of its diagonal elements greater than the absolute difference of its antidiagonal elements.

%H R. H. Hardin, <a href="/A251311/b251311.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-1) - 9*a(n-2) + 13*a(n-3) - 13*a(n-4) + 6*a(n-5) - 2*a(n-6).

%F Empirical g.f.: x*(25 - 46*x + 68*x^2 - 84*x^3 + 39*x^4 - 15*x^5) / (1 - 5*x + 9*x^2 - 13*x^3 + 13*x^4 - 6*x^5 + 2*x^6). - _Colin Barker_, Nov 28 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Column 2 of A251317.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 01 2014