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%I #8 Mar 15 2023 11:08:19
%S 9,168,42168,46008720,757664837832,53263771547091072,
%T 56395315109321439563328,254765586321230138822186989968,
%U 17333186258617759005034608109179216168
%N 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.
%C Diagonal of A223297.
%H R. H. Hardin, <a href="/A223289/b223289.txt">Table of n, a(n) for n = 1..10</a>
%e Some solutions for 3 X 3
%e ..0..1..0..5....0..3..0..7....0..3..0..3....0..3..0..6....1..0..8..0
%e ..2..0..1..0....3..0..6..0....2..0..8..0....2..0..2..0....0..3..0..5
%e ..0..6..0..1....0..2..0..6....0..1..0..1....0..8..0..1....4..0..4..0
%Y Cf. A223297.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 19 2013
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