A258560 Number of (7+1) X (n+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.

2008, 4667, 6348, 9688, 12940, 16942, 21653, 26628, 31806, 37351, 43158, 49004, 54998, 61394, 68087, 74854, 81804, 89191, 96910, 104738, 112784, 121302, 130187, 139216, 148498, 158287, 168478, 178848, 189506, 200706, 212343, 224194, 236368

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + a(n-4) - 3*a(n-5) + 3*a(n-6) - a(n-7) for n>14.

Empirical g.f.: x*(2008 - 1357*x - 1629*x^2 + 2637*x^3 - 3755*x^4 + 2195*x^5 + 1588*x^6 - 3082*x^7 + 1686*x^8 - 674*x^9 - 64*x^10 + 222*x^11 + 170*x^12 + 90*x^13) / ((1 - x)^4*(1 + x)*(1 + x^2)). - Colin Barker, Dec 22 2018

Example

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

Crossrefs

Row 7 of A258554.

Sequence in context: A201343 A219083 A258553 * A281987 A172735 A172780

Adjacent sequences: A258557 A258558 A258559 * A258561 A258562 A258563

Keyword

nonn

Author

R. H. Hardin, Jun 03 2015

Status

approved