A211926 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)/2-4

0, 0, 27, 1685, 43607, 529891, 4014522, 22135982, 97128215, 358619827, 1156561481, 3344471967, 8839393862

Offset

1,3

Comments

Column 3 of A211930

Links

Table of n, a(n) for n=1..13.

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.0......1.0......1.2......1.2......1.2......1.2
..3.4.0....3.4.5....2.1.3....2.3.0....3.4.2....3.0.4....3.4.5....3.4.1
..5.1.6.2..5.1.6.4..4.5.6.2..4.2.5.6..5.6.1.2..5.1.6.2..6.3.1.6..5.3.6.1

Crossrefs

Sequence in context: A184689 A364993 A059118 * A304119 A017199 A223476

Adjacent sequences: A211923 A211924 A211925 * A211927 A211928 A211929

Keyword

nonn

Author

R. H. Hardin Apr 25 2012

Status

approved