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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 (list; table; graph; refs; listen; history; text; internal format)
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

R. H. Hardin, Table of n, a(n) for n = 1..112

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

Adjacent sequences:  A223367 A223368 A223369 * A223371 A223372 A223373

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Mar 19 2013

STATUS

approved

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Last modified November 30 17:12 EST 2021. Contains 349424 sequences. (Running on oeis4.)