A166204 Number of nXnXn triangular nonnegative integer arrays, symmetric under 120 degree rotation, with all sums of an element and its neighbors <= 9.

1, 10, 4, 12, 201, 886, 9309, 405175, 4285591, 161588843, 25012399727, 703336933599, 84913600697770

Offset

0,2

Links

Table of n, a(n) for n=0..12.

Example

Some solutions for n=4
.....6........0........0........6........4........0........2........1...
....0.0......2.0......1.1......0.0......0.1......0.0......1.0......1.0..
...0.1.0....0.3.2....1.1.1....0.0.0....1.1.0....0.9.0....0.3.1....0.2.1.
..6.0.0.6..0.2.0.0..0.1.1.0..6.0.0.6..4.0.1.4..0.0.0.0..2.1.0.2..1.1.0.1
------
.....2........1........1........5........2........1........1........4...
....1.2......2.0......0.0......1.0......1.0......1.0......0.3......0.0..
...2.0.1....0.0.2....0.3.0....0.1.1....0.1.1....0.5.1....3.0.0....0.1.0.
..2.1.2.2..1.2.0.1..1.0.0.1..5.1.0.5..2.1.0.2..1.1.0.1..1.0.3.1..4.0.0.4

Crossrefs

Sequence in context: A100844 A076587 A266999 * A386576 A364190 A329649

Adjacent sequences: A166201 A166202 A166203 * A166205 A166206 A166207

Keyword

nonn

Author

R. H. Hardin, Oct 09 2009

Status

approved