A164746 Number of nXnXn triangular 1..3 arrays with all 1s connected, all 2s connected, all 3s connected, 1 at the top vertex, 2 at the lower left, and 3 at the lower right, and no value having more than 4 identical values adjacent.

1, 17, 159, 1448, 16770, 293511, 8049711

Offset

2,2

Links

Table of n, a(n) for n=2..8.

Example

Some solutions for n=4
......1..........1..........1..........1..........1..........1..........1....
.....1.1........2.2........1.1........3.3........1.1........3.3........3.1...
....2.1.3......2.3.2......2.2.1......3.2.3......1.2.2......2.2.3......2.3.1..
...2.1.1.3....2.3.3.3....2.2.1.3....2.2.3.3....2.2.3.3....2.3.3.3....2.3.3.3.
------
......1..........1..........1..........1..........1..........1..........1....
.....1.1........3.1........2.1........2.3........2.1........1.1........1.2...
....1.1.3......3.3.1......2.2.2......2.2.3......2.2.3......1.2.1......1.2.3..
...2.2.2.3....2.2.3.3....2.2.3.3....2.3.3.3....2.3.3.3....2.2.2.3....2.2.3.3.

Crossrefs

Sequence in context: A176622 A125380 A126538 * A198859 A160295 A125645

Adjacent sequences: A164743 A164744 A164745 * A164747 A164748 A164749

Keyword

nonn

Author

R. H. Hardin, Aug 24 2009

Status

approved