A193312 Number of n X n symmetric 0..6 arrays with no element equal to any horizontal or vertical neighbor, containing at least one 6 and with new values 0..6 introduced in lower triangular row major order.

0, 0, 0, 1967, 28086845, 1002248784605, 146362253556566778, 102707525087192055167866, 365249619799053405866337963930

Offset

1,4

Links

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

Example

Some solutions for 4 X 4
..0..1..3..5....0..1..3..5....0..1..2..4....0..1..3..4....0..1..3..4
..1..2..1..6....1..2..4..6....1..0..3..5....1..2..4..3....1..2..1..5
..3..1..4..3....3..4..0..1....2..3..2..0....3..4..5..1....3..1..3..6
..5..6..3..6....5..6..1..3....4..5..0..6....4..3..1..6....4..5..6..5

Crossrefs

Sequence in context: A235966 A252380 A251023 * A202596 A239185 A289561

Adjacent sequences: A193309 A193310 A193311 * A193313 A193314 A193315

Keyword

nonn

Author

R. H. Hardin, Jul 22 2011

Status

approved