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A223248 Two-loop graph coloring a rectangular array: number of n X n 0..4 arrays where 0..4 label nodes of a graph with edges 0,1 1,2 2,0 0,3 3,4 4,0 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph.

%I A223248 #8 Jul 23 2025 03:55:09
%S A223248 5,52,2172,307144,200258884,465277782336,5036570504598960,
%T A223248 194136255385117730696,34835929955107905273340132,
%U A223248 22243413468977139564311499153224,66105120187260568220771918409079162896
%N A223248 Two-loop graph coloring a rectangular array: number of n X n 0..4 arrays where 0..4 label nodes of a graph with edges 0,1 1,2 2,0 0,3 3,4 4,0 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph.
%C A223248 Diagonal of A223255
%H A223248 R. H. Hardin, <a href="/A223248/b223248.txt">Table of n, a(n) for n = 1..12</a>
%e A223248 Some solutions for n=3
%e A223248 ..0..1..0....1..0..1....0..3..0....4..0..2....3..0..2....3..0..3....4..0..2
%e A223248 ..3..0..2....0..2..0....2..0..3....0..1..0....0..4..0....0..4..0....0..2..1
%e A223248 ..4..3..0....3..0..1....0..3..0....1..0..4....4..0..4....3..0..3....2..0..2
%K A223248 nonn
%O A223248 1,1
%A A223248 _R. H. Hardin_ Mar 18 2013