A223366 6 X 6 X 6 triangular graph coloring a rectangular array: number of n X 4 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.

1992, 139158, 11206806, 933306108, 78876317946, 6710970374274, 573055927043172, 49029858427514634, 4199534828773389870, 359921587558219055304, 30857755579495978344822, 2646091169147364118575306

Offset

1,1

Comments

Column 4 of A223370.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Example

Some solutions for n=3
..0..2..4..2....0..1..4..2....0..1..4..8....0..2..4..3....1..2..4..1
..2..0..1..4....2..4..2..5....1..4..7..4....2..4..3..4....2..5..2..4
..4..1..4..5....5..2..4..2....3..1..3..1....4..8..4..8....5..4..5..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

Cf. A223370.

Sequence in context: A028516 A206363 A233712 * A034588 A233935 A250380

Adjacent sequences: A223363 A223364 A223365 * A223367 A223368 A223369

Keyword

nonn

Author

R. H. Hardin, Mar 19 2013

Status

approved