A223369 6X6X6 triangular graph coloring a rectangular array: number of nX7 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

221760, 250834914, 365447949798, 573055927043172, 928457167048336590, 1524391185435213940170, 2520297393549555690831036, 4179551352031701135658304214, 6944490071035753511344864688838

Offset

1,1

Comments

Column 7 of A223370

Links

R. H. Hardin, Table of n, a(n) for n = 1..71

Example

Some solutions for n=3
..0..1..0..1..3..6..3....0..1..0..2..5..2..0....0..1..0..2..5..2..5
..1..0..2..0..1..3..1....1..0..2..4..2..4..1....1..0..2..0..2..0..2
..0..2..0..1..4..7..4....0..2..0..2..5..8..4....0..2..0..1..0..2..4
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: A294014 A234489 A321160 * A366824 A254509 A254516

Adjacent sequences: A223366 A223367 A223368 * A223370 A223371 A223372

Keyword

nonn

Author

R. H. Hardin Mar 19 2013

Status

approved