A192643 Number of n X n symmetric 0..6 arrays with each element equal to at least one horizontal or vertical neighbor and any new values 0..6 introduced in lower triangular row major order

0, 1, 5, 137, 17687, 14704140, 73684193256, 2108942003884670

Offset

1,3

Links

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

Example

Some solutions for 6X6 containing a 6
..0..0..1..2..4..4....0..0..0..2..2..5....0..0..1..2..2..5....0..0..0..2..5..5
..0..0..1..2..5..5....0..0..1..2..2..5....0..0..1..3..3..5....0..0..1..2..6..6
..1..1..1..3..4..6....0..1..1..3..4..6....1..1..1..0..3..6....0..1..1..3..3..6
..2..2..3..3..4..6....2..2..3..3..4..6....2..3..0..0..4..6....2..2..3..4..4..3
..4..5..4..4..2..2....2..2..4..4..0..0....2..3..3..4..4..6....5..6..3..4..4..3
..4..5..6..6..2..2....5..5..6..6..0..0....5..5..6..6..6..6....5..6..6..3..3..3

Crossrefs

Sequence in context: A192640 A192641 A192642 * A192644 A134766 A224826

Adjacent sequences: A192640 A192641 A192642 * A192644 A192645 A192646

Keyword

nonn

Author

R. H. Hardin Jul 06 2011

Status

approved