A251086 - OEIS

A251086

Number of (n+1) X (6+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the absolute difference of its antidiagonal elements.

%I #8 Nov 24 2018 12:06:34

%S 1782,4848,8284,15780,27040,47932,82898,147152,263698,484744,907152,

%T 1730716,3347340,6546772,12900694,25558280,50809934,101242144,

%U 202019812,403478292,806280088,1611755628,3222557434,6443995840,12886683050

%N Number of (n+1) X (6+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the absolute difference of its antidiagonal elements.

%H R. H. Hardin, <a href="/A251086/b251086.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 6*a(n-1) - 13*a(n-2) + 10*a(n-3) + 5*a(n-4) - 14*a(n-5) + 9*a(n-6) - 2*a(n-7) for n>8.

%F Empirical g.f.: 2*x*(891 - 2922*x + 1181*x^2 + 5640*x^3 - 8669*x^4 + 4350*x^5 - 280*x^6 - 256*x^7) / ((1 - x)^5*(1 + x)*(1 - 2*x)). - _Colin Barker_, Nov 24 2018

%e Some solutions for n=4:

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

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

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

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

%Y Column 6 of A251088.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 29 2014