A193784 Number of n X n symmetric 0..5 arrays with no element equal to the sum or difference mod 6 of any two of its horizontal and vertical neighbors

6, 75, 1383, 82057, 17485499, 12269256241, 26618983431241, 174570423155403607, 3439388112891290777185, 203331913765001724843185283, 36063230821901471856813524283909, 19188799396869069058685453832499056759

Offset

1,1

Links

Table of n, a(n) for n=1..12.

Example

Some solutions for 4X4
..1..5..1..1....1..3..3..4....1..1..5..1....1..3..3..5....1..1..3..3
..5..3..3..3....3..3..3..3....1..3..1..5....3..3..5..5....1..1..1..5
..1..3..1..1....3..3..2..2....5..1..3..1....3..5..3..1....3..1..1..1
..1..3..1..5....4..3..2..2....1..5..1..5....5..5..1..3....3..5..1..3

Crossrefs

Sequence in context: A129031 A234529 A139088 * A162863 A216136 A360471

Adjacent sequences: A193781 A193782 A193783 * A193785 A193786 A193787

Keyword

nonn

Author

R. H. Hardin Aug 05 2011

Status

approved