A211961 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)/2-5.

0, 0, 67, 10112, 743866, 20556897, 303369413, 2935224783, 20968226394

Offset

1,3

Comments

Column 4 of A211963.

Links

Table of n, a(n) for n=1..9.

Example

Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.1......1.2......1.2......1.1......1.2......1.2......1.1
..0.2.3....2.3.4....0.3.4....3.4.3....2.3.4....3.2.3....3.3.3....0.0.2
..0.4.3.5..1.5.5.1..5.2.0.3..3.5.0.2..2.0.2.5..4.2.5.4..0.4.2.5..3.4.5.0

Crossrefs

Cf. A211963.

Sequence in context: A078989 A156121 A280004 * A144940 A211962 A263463

Adjacent sequences: A211958 A211959 A211960 * A211962 A211963 A211964

Keyword

nonn

Author

R. H. Hardin, Apr 26 2012

Status

approved