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

1,3

Comments

Column 3 of A211910

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......1.2......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

Crossrefs

Sequence in context: A241374 A233095 A223384 * A291860 A193124 A223004

Adjacent sequences: A211904 A211905 A211906 * A211908 A211909 A211910

Keyword

nonn

Author

R. H. Hardin Apr 25 2012

Status

approved