A252821 Number of n X n nonnegative integer arrays with upper left 0 and every value within 3 of its city block distance from the upper left and every value increasing by 0 or 1 with every step right or down.

1, 6, 81, 1920, 54376, 1679072, 55960651, 2001017650, 76084625352, 3047083917080, 127445868976818, 5528160760257164, 247294135503496534, 11357522219262644466, 533619846702969331737, 25573797311727396663076

Offset: 1

Author

R. H. Hardin, Dec 22 2014

Keywords

• nonn

Comments

Diagonal of A252828

Examples

			Some solutions for n=4
..0..1..2..3....0..1..1..2....0..1..1..2....0..1..2..3....0..1..2..2
..0..1..2..3....0..1..2..3....0..1..1..2....1..2..3..4....0..1..2..2
..1..2..3..4....1..2..3..3....0..1..2..3....2..3..3..4....1..2..3..3
..2..3..4..5....2..2..3..4....1..2..2..3....3..4..4..5....2..3..3..3
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..25