A266028 Number of n X 3 integer arrays with each element equal to the number of horizontal and antidiagonal neighbors less than itself.

5, 50, 481, 4659, 45361, 440405, 4281953, 41605113, 404371841, 3929676961, 38190819553, 371149900881, 3606990493057, 35054056081937, 340669003487777, 3310750747302897, 32175148917943745, 312690400948679185

Offset

1,1

Links

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

Formula

Empirical: a(n) = 5*a(n-1) + 46*a(n-2) + 6*a(n-3) - 72*a(n-4).

Empirical g.f.: x*(1 + 4*x)*(5 + 5*x - 19*x^2) / (1 - 5*x - 46*x^2 - 6*x^3 + 72*x^4). - Colin Barker, Jan 09 2019

Example

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

Crossrefs

Column 3 of A266033.

Sequence in context: A247771 A125962 A361555 * A228751 A299868 A136915

Adjacent sequences: A266025 A266026 A266027 * A266029 A266030 A266031

Keyword

nonn

Author

R. H. Hardin, Dec 20 2015

Status

approved