A211959 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any diagonal or antidiagonal neighbor, and containing the value n(n+1)/2-3

0, 3, 43, 499, 3304, 15021, 53038, 156458, 403574, 938134, 2006916, 4011448, 7577023, 13642474, 23574489, 39310561, 63534983, 99892613, 153245449, 229977369, 338352706, 488934643, 695069728

Offset

1,2

Comments

Column 2 of A211963

Links

Table of n, a(n) for n=1..23.

Formula

Empirical: a(n) = (1/128)*n^8 + (1/32)*n^7 - (29/192)*n^6 - (3/16)*n^5 + (209/128)*n^4 - (205/96)*n^3 - (47/96)*n^2 + (79/24)*n - 1 for n>1

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.1......1.2......1.2......1.2......1.1
..3.4.5....3.4.0....3.3.4....2.3.4....3.4.4....3.4.0....3.2.4....2.2.3
..6.6.3.7..5.1.6.7..5.6.4.7..5.6.1.7..5.6.7.2..5.6.7.7..1.5.6.7..4.5.6.7

Crossrefs

Sequence in context: A173770 A093163 A199020 * A283514 A299506 A350924

Adjacent sequences: A211956 A211957 A211958 * A211960 A211961 A211962

Keyword

nonn

Author

R. H. Hardin Apr 26 2012

Status

approved