A193225 Number of n X n symmetric 0..7 arrays with no element equal to the sum mod 8 of any two of its horizontal and vertical neighbors

8, 343, 54769, 34412915, 85151401909, 832274517610173

Offset

1,1

Links

Table of n, a(n) for n=1..6.

Example

Some solutions for 4X4
..4..4..4..2....0..6..2..6....4..4..4..4....0..2..4..4....0..2..4..4
..4..4..7..2....6..2..6..3....4..4..5..4....2..0..3..4....2..0..7..2
..4..7..2..6....2..6..7..0....4..5..6..5....4..3..4..7....4..7..1..7
..2..2..6..6....6..3..0..6....4..4..5..4....4..4..7..0....4..2..7..3

Crossrefs

Sequence in context: A002781 A016875 A046244 * A304148 A305488 A305088

Adjacent sequences: A193222 A193223 A193224 * A193226 A193227 A193228

Keyword

nonn

Author

R. H. Hardin Jul 18 2011

Status

approved