A211915 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, vertical, diagonal or antidiagonal neighbor, and containing the value n(n+1)/2-6.
0, 0, 10, 1732, 1085432, 146208485, 6410611003, 140836842878
Offset: 1
Keywords
Examples
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 ..3.4.1....3.0.3....0.3.4....3.4.0....3.4.5....3.0.4....0.3.1....3.0.4 ..1.0.5.3..2.4.5.6..5.1.6.3..5.1.5.3..2.1.0.3..5.2.6.0..2.4.2.4..4.5.3.6
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