A212032 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any element at a city block distance of two, and containing the value n(n+1)/2-3.

0, 3, 28, 338, 2440, 11859, 43943, 134273, 355568, 843290, 1832469, 3708583, 7075643, 12844948, 22348290, 37479704, 60870173, 96100013, 147953978, 222724440, 328568314, 475923713

Offset

1,2

Comments

Column 2 of A212036

Links

Table of n, a(n) for n=1..22.

Formula

Empirical: a(n) = (1/128)*n^8 + (1/32)*n^7 - (53/192)*n^6 - (1/16)*n^5 + (545/128)*n^4 - (1129/96)*n^3 + (913/96)*n^2 + (175/24)*n - 10 for n>1

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......0.1......1.2......1.2......1.2......1.2......0.1......1.2
..3.4.5....2.3.4....3.4.4....3.3.0....1.3.4....1.3.4....2.3.4....3.4.5
..6.0.7.6..5.6.2.7..5.6.6.7..4.5.6.7..5.6.7.3..5.6.7.2..5.6.6.7..0.6.7.0

Crossrefs

Sequence in context: A176335 A072343 A292845 * A352383 A151423 A161605

Adjacent sequences: A212029 A212030 A212031 * A212033 A212034 A212035

Keyword

nonn

Author

R. H. Hardin, Apr 27 2012

Status

approved