A251049 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.

290, 1528, 4334, 11280, 25847, 56676, 118925, 247753, 515324, 1087674, 2331944, 5093511, 11294058, 25360220, 57445566, 130937588, 299629648, 687412847, 1579482633, 3632619857, 8359090437, 19241386917, 44298667688, 101997419499

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

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.

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

Example

Some solutions for n=4:
..0..1..2....1..0..3....1..0..3....0..0..2....2..3..3....1..3..3....0..0..2
..0..0..0....1..0..3....1..0..3....0..0..0....0..0..0....0..0..0....0..0..2
..3..3..3....1..0..1....1..0..3....0..0..0....0..0..0....3..3..3....0..0..1
..0..0..0....1..0..0....2..0..1....1..0..0....1..0..0....0..0..0....0..0..0
..0..0..0....2..1..1....3..0..1....2..0..0....3..2..1....3..3..1....3..3..3

Crossrefs

Column 2 of A251055.

Sequence in context: A295483 A075299 A031712 * A108881 A186547 A237741

Adjacent sequences: A251046 A251047 A251048 * A251050 A251051 A251052

Keyword

nonn

Author

R. H. Hardin, Nov 29 2014

Status

approved