A192644 Number of n X n symmetric 0..7 arrays with each element equal to at least one horizontal or vertical neighbor and any new values 0..7 introduced in lower triangular row major order.

0, 1, 5, 137, 17687, 14743487, 78148721677, 2854620794876552

Offset

1,3

Links

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

Example

Some solutions for 6 X 6 containing a 7:
..0..0..1..1..5..5....0..0..2..2..5..5....0..0..0..2..4..4....0..0..0..2..5..7
..0..0..2..3..6..6....0..1..1..3..5..5....0..0..1..2..5..5....0..0..1..2..5..7
..1..2..2..3..4..5....2..1..3..3..6..6....0..1..1..3..6..7....0..1..1..3..3..7
..1..3..3..4..4..5....2..3..3..4..4..4....2..2..3..3..6..7....2..2..3..4..4..6
..5..6..4..4..4..7....5..5..6..4..7..7....4..5..6..6..4..4....5..5..3..4..6..6
..5..6..5..5..7..7....5..5..6..4..7..7....4..5..7..7..4..4....7..7..7..6..6..6

Crossrefs

Sequence in context: A192641 A192642 A192643 * A134766 A224826 A122911

Adjacent sequences: A192641 A192642 A192643 * A192645 A192646 A192647

Keyword

nonn,more

Author

R. H. Hardin, Jul 06 2011

Status

approved