A251049 - OEIS

%I #8 Nov 24 2018 08:13:06

%S 290,1528,4334,11280,25847,56676,118925,247753,515324,1087674,2331944,

%T 5093511,11294058,25360220,57445566,130937588,299629648,687412847,

%U 1579482633,3632619857,8359090437,19241386917,44298667688,101997419499

%N Number of (n+1) X (2+1) 0..3 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="/A251049/b251049.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 8*a(n-1) - 25*a(n-2) + 35*a(n-3) - 7*a(n-4) - 49*a(n-5) + 77*a(n-6) - 55*a(n-7) + 20*a(n-8) - 3*a(n-9) for n>11.

%F Empirical g.f.: x*(290 - 792*x - 640*x^2 + 4658*x^3 - 7493*x^4 + 5116*x^5 - 228*x^6 - 1772*x^7 + 936*x^8 - 113*x^9 - 19*x^10) / ((1 - x)^7*(1 - x - 3*x^2)). - _Colin Barker_, Nov 24 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Column 2 of A251055.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 29 2014