A193273 Number of n X n symmetric 0..7 arrays with no element equal to any horizontal or vertical neighbor and with new values 0..7 introduced in lower triangular row major order

1, 2, 42, 12806, 71531470, 4359452409293, 1840118598465187309, 4839010680027431179628037, 78256880677789721019902991767596

Offset

1,2

Links

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

Example

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

Crossrefs

Sequence in context: A278150 A193271 A193272 * A182192 A330229 A039622

Adjacent sequences: A193270 A193271 A193272 * A193274 A193275 A193276

Keyword

nonn

Author

R. H. Hardin Jul 20 2011

Status

approved