A251151 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having the minimum of its diagonal elements greater than the absolute difference of its antidiagonal elements.

65, 470, 3374, 24233, 173990, 1249276, 8969854, 64404093, 462424885, 3320236303, 23839479611, 171168778796, 1229001271939, 8824296918154, 63358938568631, 454920673442317, 3266355526135404, 23452612831159266, 168391053639773507

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) + 4*a(n-2) - 20*a(n-3) + 3*a(n-4) + 8*a(n-5) - 4*a(n-6).

Empirical g.f.: x*(65 + 15*x - 176*x^2 + 35*x^3 + 68*x^4 - 36*x^5) / (1 - 7*x - 4*x^2 + 20*x^3 - 3*x^4 - 8*x^5 + 4*x^6). - Colin Barker, Nov 26 2018

Example

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

Crossrefs

Column 1 of A251158.

Sequence in context: A219424 A020292 A251158 * A222588 A286612 A276963

Adjacent sequences: A251148 A251149 A251150 * A251152 A251153 A251154

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved