A250512 Number of (n+1)X(1+1) 0..3 arrays with nondecreasing min(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.

120, 889, 5996, 39187, 248942, 1555689, 9605300, 58826247, 358185874, 2172028005, 13132419904, 79233189251, 477317759278, 2872297644737, 17270479247100, 103783325757983, 623401528654314, 3743476771002397, 22474273340351352

Offset

1,1

Links

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

Formula

Empirical: a(n) = 10*a(n-1) - 15*a(n-2) - 80*a(n-3) + 122*a(n-4) + 228*a(n-5) - 120*a(n-6) - 144*a(n-7).

Empirical g.f.: x*(120 - 311*x - 1094*x^2 + 2162*x^3 + 3492*x^4 - 2064*x^5 - 2304*x^6) / ((1 - x)*(1 + 2*x)*(1 - 6*x)*(1 - 2*x - 2*x^2)*(1 - 3*x - 6*x^2)). - Colin Barker, Nov 14 2018

Example

Some solutions for n=4:
..3..0....0..0....1..2....1..0....1..2....2..0....0..0....0..0....1..2....0..3
..0..0....0..0....1..3....0..0....3..1....0..1....0..0....3..0....1..2....0..1
..0..0....0..1....3..1....0..2....1..3....3..1....1..2....0..1....1..3....0..2
..2..0....0..0....1..2....1..3....2..2....1..1....1..2....1..0....2..3....2..0
..0..1....0..1....2..1....2..2....2..3....2..2....3..3....0..0....2..2....0..0

Crossrefs

Column 1 of A250519.

Sequence in context: A029573 A211471 A250519 * A011245 A213875 A092182

Adjacent sequences: A250509 A250510 A250511 * A250513 A250514 A250515

Keyword

nonn

Author

R. H. Hardin, Nov 24 2014

Status

approved