A211914 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal, vertical, diagonal or antidiagonal neighbor, and containing the value n(n+1)/2-5

0, 0, 10, 1492, 227388, 9345480, 172044141, 1908272916, 14931819099

Offset

1,3

Comments

Column 4 of A211916

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
..3.0.4....3.4.0....3.4.3....3.4.5....0.3.4....0.3.1....3.4.0....3.0.4
..1.5.3.1..5.1.6.4..5.6.5.1..0.6.0.6..5.6.5.2..2.4.0.5..1.5.6.5..1.2.1.5

Crossrefs

Sequence in context: A160104 A361495 A370678 * A194792 A133216 A099128

Adjacent sequences: A211911 A211912 A211913 * A211915 A211916 A211917

Keyword

nonn

Author

R. H. Hardin Apr 25 2012

Status

approved