A250809 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 min(x(i,j),x(i-1,j)) in the j direction.

784, 3097, 11116, 37333, 120304, 377857, 1167796, 3572173, 10854424, 32839417, 99070876, 298318213, 897166144, 2695921777, 8096612356, 24307531453, 72957983464, 218944728937, 656975744236, 1971210347893, 5914197274384

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) = (1131*3^n - 1080*2^n + 335)/2.

Empirical g.f.: x*(784 - 1607*x + 1158*x^2) / ((1 - x)*(1 - 2*x)*(1 - 3*x)). - Colin Barker, Nov 20 2018

Example

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

Crossrefs

Column 5 of A250812.

Sequence in context: A257355 A187935 A258539 * A255145 A203790 A223493

Adjacent sequences: A250806 A250807 A250808 * A250810 A250811 A250812

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved