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A223370
T(n,k)=6X6X6 triangular graph coloring a rectangular array: number of nXk 0..20 arrays where 0..20 label nodes of the fully triangulated graph and every array movement to a horizontal or vertical neighbor moves along an edge of this graph
8
21, 90, 90, 420, 990, 420, 1992, 11610, 11610, 1992, 9552, 139158, 357354, 139158, 9552, 45984, 1686042, 11206806, 11206806, 1686042, 45984, 221760, 20537766, 356391222, 933306108, 356391222, 20537766, 221760, 1070208, 250834914
OFFSET
1,1
COMMENTS
Table starts
.......21...........90...............420..................1992
.......90..........990.............11610................139158
......420........11610............357354..............11206806
.....1992.......139158..........11206806.............933306108
.....9552......1686042.........356391222...........78876317946
....45984.....20537766.......11391019146.........6710970374274
...221760....250834914......365447949798.......573055927043172
..1070208...3067525350....11741128578822.....49029858427514634
..5166336..37537522362...377630573527206...4199534828773389870
.24943104.459492912054.12150390210921654.359921587558219055304
LINKS
EXAMPLE
Some solutions for n=3 k=4
..0..2..0..2....1..2..0..1....0..1..4..3....0..1..3..1....0..2..0..2
..2..0..2..4....2..5..2..0....1..4..1..4....1..2..4..2....2..4..2..4
..5..2..4..2....1..2..5..2....3..1..3..7....4..5..2..1....1..2..1..2
Vertex neighbors:
0 -> 1 2
1 -> 0 2 3 4
2 -> 0 1 4 5
3 -> 1 4 6 7
4 -> 1 2 3 5 7 8
5 -> 2 4 8 9
6 -> 3 7 10 11
7 -> 3 4 6 8 11 12
8 -> 4 5 7 9 12 13
9 -> 5 8 13 14
10 -> 6 11 15 16
11 -> 6 7 10 12 16 17
12 -> 7 8 11 13 17 18
13 -> 8 9 12 14 18 19
14 -> 9 13 19 20
15 -> 10 16
16 -> 10 11 15 17
17 -> 11 12 16 18
18 -> 12 13 17 19
19 -> 13 14 18 20
20 -> 14 19
CROSSREFS
Sequence in context: A219886 A211464 A268257 * A223363 A284440 A020248
KEYWORD
nonn,tabl
AUTHOR
R. H. Hardin Mar 19 2013
STATUS
approved