A250752 Number of (n+1) X (5+1) 0..2 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)+x(i-1,j) in the j direction.

294, 957, 3066, 9633, 29814, 91317, 277746, 840873, 2537934, 7644477, 22994826, 69107313, 207567654, 623194437, 1870566306, 5613664953, 16844926974, 50542645197, 151643664186, 454962449793, 1364950263894, 4094976620757

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3); a(n) = (261*3^n - 120*2^n + 45)/2.

Empirical g.f.: 3*x*(98 - 269*x + 186*x^2) / ((1 - x)*(1 - 2*x)*(1 - 3*x)). - Colin Barker, Nov 17 2018

Example

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

Crossrefs

Column 5 of A250755.

Sequence in context: A255104 A212724 A235948 * A235007 A235002 A222798

Adjacent sequences: A250749 A250750 A250751 * A250753 A250754 A250755

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved