A252869 Number of n X n nonnegative integer arrays with upper left 0 and lower right 2n-4 and value increasing by 0 or 1 with every step right or down.

0, 1, 44, 615, 7313, 85801, 1030330, 12742873, 161937617, 2105918045, 27918122131, 376111502977, 5136280530303, 70961632168027, 990271171218092, 13940676224604419, 197768060575469207, 2824828302263709187, 40595088350375470407, 586585037283553891311

Offset: 1

Author

R. H. Hardin, Dec 24 2014

Keywords

• nonn

Examples

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

Crossrefs

Main diagonal of A252876.

Column d=2 of A323849.

Extensions

a(16)-a(20) from Alois P. Heinz, Feb 07 2019