A251310 Number of (n+1) X (1+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.

10, 25, 61, 149, 365, 894, 2189, 5360, 13125, 32139, 78698, 192706, 471875, 1155470, 2829374, 6928226, 16964995, 41541811, 101722521, 249085705, 609930700, 1493523921, 3657159252, 8955205609, 21928415465, 53695629760, 131483310316

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 2*a(n-3) - a(n-4).

Empirical g.f.: x*(10 - 5*x + 6*x^2 - 4*x^3) / (1 - 3*x + 2*x^2 - 2*x^3 + x^4). - Colin Barker, Nov 28 2018

Example

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

Crossrefs

Column 1 of A251317.

Sequence in context: A263310 A063424 A137930 * A251194 A071289 A268303

Adjacent sequences: A251307 A251308 A251309 * A251311 A251312 A251313

Keyword

nonn

Author

R. H. Hardin, Dec 01 2014

Status

approved