A233195 Number of n X n 0..7 arrays with no element x(i,j) adjacent to itself or value 7-x(i,j) horizontally, antidiagonally or vertically, top left element zero, and 1 appearing before 2 3 4 5 and 6, 2 appearing before 3 4 and 5, and 3 appearing before 4 in row major order (unlabelled 8-colorings with no clashing color pairs)

1, 3, 1440, 7802880, 352524959744, 132364161848967168, 416547612309880393695232, 11042955940877644659574580445184, 2474201164323675429580723288914257772544

Offset

1,2

Comments

Diagonal of A233202

Links

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

Example

Some solutions for n=3
..0..1..2....0..1..2....0..1..2....0..1..7....0..1..0....0..1..2....0..1..2
..5..0..6....5..0..6....2..3..7....2..3..1....2..3..5....3..0..1....5..7..3
..6..5..3....3..5..7....6..5..4....1..7..4....6..7..3....1..2..3....4..2..0

Crossrefs

Sequence in context: A262516 A060307 A119111 * A219783 A264427 A285656

Adjacent sequences: A233192 A233193 A233194 * A233196 A233197 A233198

Keyword

nonn

Author

R. H. Hardin, Dec 05 2013

Status

approved