A193000 Number of n X n symmetric 0..6 arrays with each element equal to at least two horizontal or vertical neighbors and with new values 0..6 introduced in lower triangular row major order

0, 1, 1, 6, 35, 697, 19477, 1565794, 210688406, 77029067005

Offset

1,4

Links

Table of n, a(n) for n=1..10.

Example

Some solutions for 8X8 containing a 6
..0..0..0..1..1..1..0..0....0..0..1..1..3..3..4..4....0..0..1..1..3..3..5..5
..0..0..0..1..1..1..0..0....0..0..1..1..3..3..4..4....0..0..1..1..3..3..5..5
..0..0..1..1..2..2..4..4....1..1..2..2..4..4..5..5....1..1..2..2..1..1..0..0
..1..1..1..1..2..2..4..4....1..1..2..2..4..4..5..5....1..1..2..2..1..1..0..0
..1..1..2..2..3..3..5..5....3..3..4..4..3..3..1..1....3..3..1..1..4..4..6..6
..1..1..2..2..3..3..5..5....3..3..4..4..3..3..1..1....3..3..1..1..4..4..6..6
..0..0..4..4..5..5..6..6....4..4..5..5..1..1..6..6....5..5..0..0..6..6..6..6
..0..0..4..4..5..5..6..6....4..4..5..5..1..1..6..6....5..5..0..0..6..6..6..6

Crossrefs

Sequence in context: A115457 A192998 A192999 * A193001 A128298 A059059

Adjacent sequences: A192997 A192998 A192999 * A193001 A193002 A193003

Keyword

nonn

Author

R. H. Hardin Jul 14 2011

Status

approved