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A223289
4-loop graph coloring a rectangular array: number of n X n 0..8 arrays where 0..8 label nodes of a graph with edges 0,1 1,2 2,0 0,3 3,4 4,0 0,5 5,6 6,0 0,7 7,8 8,0 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph.
1
9, 168, 42168, 46008720, 757664837832, 53263771547091072, 56395315109321439563328, 254765586321230138822186989968, 17333186258617759005034608109179216168
OFFSET
1,1
COMMENTS
Diagonal of A223297.
LINKS
EXAMPLE
Some solutions for 3 X 3
..0..1..0..5....0..3..0..7....0..3..0..3....0..3..0..6....1..0..8..0
..2..0..1..0....3..0..6..0....2..0..8..0....2..0..2..0....0..3..0..5
..0..6..0..1....0..2..0..6....0..1..0..1....0..8..0..1....4..0..4..0
CROSSREFS
Cf. A223297.
Sequence in context: A367139 A180819 A132874 * A281996 A017306 A210089
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 19 2013
STATUS
approved