A182367 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any diagonal or antidiagonal neighbor

1, 3, 67, 21350, 147512732, 30761087800216

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......1.1......1.2......1.2......1.2......0.1......0.1
..1.2.1....3.3.4....2.3.4....0.3.0....0.3.3....3.2.3....0.2.2....2.3.4
..3.2.4.0..4.5.1.2..5.3.6.0..2.1.1.3..4.5.6.7..3.1.4.0..0.3.0.1..2.5.0.6

Crossrefs

Sequence in context: A186208 A217625 A238316 * A091872 A079320 A283882

Adjacent sequences: A182364 A182365 A182366 * A182368 A182369 A182370

Keyword

nonn

Author

R. H. Hardin Apr 26 2012

Status

approved