A250873 Number of (n+1) X (4+1) 0..3 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.

1328, 6728, 31928, 144248, 629528, 2681528, 11227928, 46440248, 190392728, 775558328, 3144379928, 12704328248, 51198475928, 205938867128, 827193307928, 3319092648248, 13307340639128, 53322296287928, 213568033531928

Offset

1,1

Links

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

Formula

Empirical: a(n) = 10*a(n-1) - 35*a(n-2) + 50*a(n-3) - 24*a(n-4); a(n) = (2340*4^n - 2160*3^n + 540*2^n + 24)/3.

Empirical g.f.: 8*x*(166 - 819*x + 1391*x^2 - 744*x^3) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)). - Colin Barker, Nov 22 2018

Example

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

Crossrefs

Column 4 of A250877.

Sequence in context: A082889 A109568 A235234 * A205091 A038854 A323329

Adjacent sequences: A250870 A250871 A250872 * A250874 A250875 A250876

Keyword

nonn

Author

R. H. Hardin, Nov 28 2014

Status

approved