A182382 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any element at a city block distance of two.

1, 3, 34, 5587, 22019098, 2777234353850

Offset

1,2

Links

Table of n, a(n) for n=1..6.

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......0.1......1.2......1.2......1.2......1.2
..3.2.4....3.4.0....3.4.5....2.2.3....1.3.4....1.3.0....3.3.1....3.3.1
..5.5.3.3..5.1.0.4..0.6.3.4..4.4.5.1..0.3.2.0..0.4.4.1..4.4.5.6..2.0.4.2

Crossrefs

Sequence in context: A197434 A194891 A194892 * A222787 A180126 A214854

Adjacent sequences: A182379 A182380 A182381 * A182383 A182384 A182385

Keyword

nonn

Author

R. H. Hardin, Apr 27 2012

Status

approved