A212042 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 within a city block distance of two, and containing the value n(n+1)/2-5

0, 0, 5, 447, 94131, 5054845, 109065807, 1339229741, 11235618109

Offset

1,3

Comments

Column 4 of A212044

Links

Table of n, a(n) for n=1..9.

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.2......1.2......1.2......1.2......1.2
..3.4.0....3.0.4....3.4.0....3.0.4....3.4.5....3.4.5....3.0.4....3.4.5
..0.5.3.4..5.1.2.5..5.6.3.5..5.6.7.5..5.0.6.2..2.1.0.2..5.1.6.2..6.7.2.1

Crossrefs

Sequence in context: A145247 A317345 A333263 * A177026 A300544 A055305

Adjacent sequences: A212039 A212040 A212041 * A212043 A212044 A212045

Keyword

nonn

Author

R. H. Hardin Apr 28 2012

Status

approved