A211927 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 or antidiagonal neighbor, and containing the value n(n+1)/2-5

0, 0, 27, 4151, 425384, 14087170, 230476122, 2379082308, 17753221488

Offset

1,3

Comments

Column 4 of A211930

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....0.3.1....3.4.0....3.4.5....0.3.4....3.4.5....3.4.0....3.4.3
..1.5.6.7..4.2.0.5..2.5.4.2..5.0.1.4..5.6.1.0..0.1.4.0..1.5.4.5..5.2.0.5

Crossrefs

Sequence in context: A230169 A271240 A223327 * A298595 A278686 A046367

Adjacent sequences: A211924 A211925 A211926 * A211928 A211929 A211930

Keyword

nonn

Author

R. H. Hardin Apr 25 2012

Status

approved