A250753 Number of (n+1) X (6+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.

402, 1305, 4182, 13149, 40722, 124785, 379662, 1149669, 3470442, 10454265, 31448742, 94518189, 283898562, 852383745, 2558527422, 7678334709, 23040509082, 69132537225, 207419631702, 622302935229, 1866996886002, 5601166818705

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) = (357*3^n - 168*2^n + 69)/2.

Empirical g.f.: 3*x*(134 - 369*x + 258*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..1....1..1..1..1..1..1..1....1..1..1..1..1..1..1
..0..0..0..0..0..0..0....0..0..0..0..0..0..0....1..1..1..1..2..2..2
..2..2..2..2..2..2..2....2..2..2..2..2..2..2....0..0..0..0..1..1..1
..0..1..1..2..2..2..2....2..2..2..2..2..2..2....1..1..1..1..2..2..2
..0..1..1..2..2..2..2....0..0..0..0..0..0..1....0..0..0..1..2..2..2

Crossrefs

Column 6 of A250755.

Sequence in context: A115244 A031518 A104391 * A158312 A237177 A128767

Adjacent sequences: A250750 A250751 A250752 * A250754 A250755 A250756

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved