A193786 Number of n X n symmetric 0..7 arrays with no element equal to the sum or difference mod 8 of any two of its horizontal and vertical neighbors

8, 225, 12385, 2332419, 1850486123, 6771682819965, 107524741264745861, 7041765967963842788487

Offset

1,1

Links

Table of n, a(n) for n=1..8.

Example

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

Crossrefs

Sequence in context: A214383 A220546 A189445 * A213799 A316809 A299655

Adjacent sequences: A193783 A193784 A193785 * A193787 A193788 A193789

Keyword

nonn

Author

R. H. Hardin Aug 05 2011

Status

approved