A211909 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 or vertical neighbor, and containing the value n(n+1)/2-6

0, 0, 42, 11296, 3997836, 350026718, 12075054829, 228741733963

Offset

1,3

Comments

Column 5 of A211910

Links

Table of n, a(n) for n=1..8.

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.2......1.2......1.0......1.2......1.2
..2.3.2....0.3.0....0.3.4....3.4.3....2.1.3....2.3.2....2.3.2....3.0.4
..4.1.4.0..4.5.2.6..3.0.2.0..5.0.5.3..4.0.4.3..4.2.0.1..3.4.3.1..4.5.2.0

Crossrefs

Sequence in context: A303055 A226262 A109817 * A289396 A159417 A289540

Adjacent sequences: A211906 A211907 A211908 * A211910 A211911 A211912

Keyword

nonn

Author

R. H. Hardin Apr 25 2012

Status

approved