A250788 Number of (6+1) X (n+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.

288, 796, 2010, 5028, 12036, 27986, 63184, 139436, 301786, 643164, 1353544, 2820050, 5828064, 11966884, 24444622, 49725780, 100817008, 203857762, 411330612, 828530748, 1666582118, 3348596476, 6722194620, 13484879538

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 18*a(n-2) + 17*a(n-3) + 8*a(n-4) - 29*a(n-5) + 18*a(n-6) + 3*a(n-7) - 7*a(n-8) + 2*a(n-9).

Empirical g.f.: 2*x*(144 - 610*x + 811*x^2 + 195*x^3 - 1408*x^4 + 1026*x^5 + 137*x^6 - 421*x^7 + 128*x^8) / ((1 - x)^5*(1 + x)*(1 - 2*x)*(1 - x - x^2)). - Colin Barker, Nov 20 2018

Example

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

Crossrefs

Row 6 of A250783.

Sequence in context: A127350 A158253 A292054 * A179646 A281236 A237369

Adjacent sequences: A250785 A250786 A250787 * A250789 A250790 A250791

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved