login
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
1, 2, 42, 12806, 71531470, 4359452409293, 1840118598465187309, 4839010680027431179628037, 78256880677789721019902991767596
OFFSET
1,2
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
KEYWORD
nonn
AUTHOR
R. H. Hardin Jul 20 2011
STATUS
approved