A250852 Number of (n+1) X (7+1) 0..3 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.

27225, 198297, 1195457, 6279401, 30214465, 137379337, 601566177, 2567402601, 10763029505, 44552408777, 182750596897, 744705474601, 3020091585345, 12204496276617, 49191016683617, 197884445031401, 794901482169985

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) = (562288*4^n - 939120*3^n + 470064*2^n - 45220)/12.

Empirical g.f.: x*(27225 - 73953*x + 165362*x^2 - 96024*x^3) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)). - Colin Barker, Nov 21 2018

Example

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

Crossrefs

Column 7 of A250853.

Sequence in context: A268358 A157814 A216943 * A157820 A251777 A032746

Adjacent sequences: A250849 A250850 A250851 * A250853 A250854 A250855

Keyword

nonn

Author

R. H. Hardin, Nov 28 2014

Status

approved