A200770 Number of nX1 0..2 arrays with every row and column running average nondecreasing rightwards and downwards, and the number of instances of each value within one of each other.

3, 3, 2, 7, 9, 6, 22, 30, 20, 75, 105, 70, 266, 378, 252, 966, 1386, 924, 3564, 5148, 3432, 13299, 19305, 12870, 50050, 72930, 48620, 189618, 277134, 184756, 722228, 1058148, 705432, 2762942, 4056234, 2704156, 10608612, 15600900, 10400600, 40859500, 60174900

Offset

1,1

Links

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

Formula

Conjecture: (n+2)*(2770*n-4893)*a(n) + 3*(1090*n^2-4919*n+1654)*a(n-1) + 4686*a(n-2) + 2*(-5540*n^2+7016*n+17127)*a(n-3) - 6*(1090*n-2739)*(2*n-7)*a(n-4) = 0. - R. J. Mathar, Nov 23 2011 [corrected by Jason Yuen, Oct 14 2025]

Example

All solutions for n=4
..0....0....0....0....0....0....0
..0....2....0....1....1....1....2
..1....1....2....2....2....1....1
..2....2....1....2....1....2....1

Crossrefs

Column 1 of A200777.

Includes A003409((n+1)/3) and A000984(n/3).

Sequence in context: A115055 A158468 A238278 * A265965 A192787 A388894

Adjacent sequences: A200767 A200768 A200769 * A200771 A200772 A200773

Keyword

nonn

Author

R. H. Hardin, Nov 22 2011

Status

approved