|
%I #6 Dec 18 2015 18:18:30
%S 16,328,39480,26836512,102163935000,2167784359988816,
%T 255768507759156858992,167580379521857073501154504,
%U 609297766107012047545889012846856
%N 4X4 square grid graph coloring a rectangular array: number of n X n 0..15 arrays where 0..15 label nodes of the square grid graph and every array movement to a horizontal or vertical neighbor moves along an edge of this graph
%C Diagonal of A223402
%H R. H. Hardin, <a href="/A223394/b223394.txt">Table of n, a(n) for n = 1..10</a>
%e Some solutions for n=3
%e ..2..6..7....7..6.10....2..3..7....5..6..2....7.11.15...11.10.14...11..7..6
%e ..6.10..6...11.10.11....6..7.11....6..5..6...11.10.11...10..9.10....7..3..7
%e .10..6.10...15.11.10....5..6..7....5..9..5...10.11.10....6.10.11....3..7..6
%e Vertex neighbors:
%e 0 -> 1 4
%e 1 -> 0 2 5
%e 2 -> 1 3 6
%e 3 -> 2 7
%e 4 -> 0 5 8
%e 5 -> 4 1 6 9
%e 6 -> 5 2 7 10
%e 7 -> 6 3 11
%e 8 -> 4 9 12
%e 9 -> 8 5 10 13
%e 10 -> 9 6 11 14
%e 11 -> 10 7 15
%e 12 -> 8 13
%e 13 -> 12 9 14
%e 14 -> 13 10 15
%e 15 -> 14 11
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 19 2013
| 