A250633 Number of (1+1) X (n+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.

36, 154, 585, 2183, 7924, 28456, 101308, 358990, 1268051, 4470464, 15740673, 55379788, 194741827, 684584785, 2406055663, 8455258981, 29710611016, 104393359779, 366791460582, 1288712370834, 4527794056964, 15907920902171

Offset

1,1

Links

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

Formula

Empirical: a(n) = 5*a(n-1) - 2*a(n-2) - 14*a(n-3) + 7*a(n-4) + 10*a(n-5) - 5*a(n-6) - 2*a(n-7) + a(n-8).

Empirical g.f.: x*(36 - 26*x - 113*x^2 + 70*x^3 + 83*x^4 - 46*x^5 - 17*x^6 + 9*x^7) / ((1 - 2*x - x^2 + x^3)*(1 - 3*x - 3*x^2 + 4*x^3 + x^4 - x^5)). - Colin Barker, Nov 15 2018

Example

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

Crossrefs

Row 1 of A250632.

Sequence in context: A211739 A211748 A211757 * A211759 A064244 A280397

Adjacent sequences: A250630 A250631 A250632 * A250634 A250635 A250636

Keyword

nonn

Author

R. H. Hardin, Nov 26 2014

Status

approved