A211907 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)/2-4.

0, 0, 41, 2385, 55822, 637721, 4639742, 24871596, 106911695, 388681117, 1238600816, 3548005682, 9306274551

Offset: 1

Author

R. H. Hardin Apr 25 2012

Keywords

• nonn

Comments

Column 3 of A211910

Examples

			Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.0......1.2......1.2......1.0......1.2......1.0
..3.4.5....0.3.2....2.3.4....3.4.2....3.4.3....2.3.4....3.1.4....2.1.3
..6.3.0.6..4.5.3.6..1.0.5.6..0.3.5.6..4.5.2.6..5.2.6.5..5.6.3.4..1.4.5.6