A212023 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, diagonal or antidiagonal neighbor, and containing the value n(n+1)/2-4

0, 0, 34, 1793, 44294, 532619, 4022727, 22156544, 97173498, 358710379, 1156729484, 3344765527, 8839882229

Offset

1,3

Comments

Column 3 of A212026

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......1.2......1.2......1.2......1.2......1.2......1.2
..3.4.0....3.4.3....3.4.3....3.4.3....3.4.0....1.3.4....3.0.4....1.3.4
..1.5.6.1..5.4.6.4..5.2.0.6..5.6.3.6..1.5.2.6..5.2.1.6..4.1.5.6..5.0.6.0

Crossrefs

Sequence in context: A202297 A296673 A086881 * A056566 A335090 A242177

Adjacent sequences: A212020 A212021 A212022 * A212024 A212025 A212026

Keyword

nonn

Author

R. H. Hardin Apr 26 2012

Status

approved