A166203 Number of nXnXn triangular nonnegative integer arrays, symmetric under 120 degree rotation, with all sums of an element and its neighbors <= 8

1, 9, 3, 10, 138, 579, 5166, 172012, 1571016, 46316901, 5087344969, 113781268522, 9916013916442

Offset

0,2

Links

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

Example

Some solutions for n=4
.....4........2........5........1........1........0........2........8...
....1.1......1.0......1.1......1.0......0.0......1.1......2.0......0.0..
...1.0.1....0.0.1....1.0.1....0.0.1....0.6.0....1.1.1....0.0.2....0.0.0.
..4.1.1.4..2.1.0.2..5.1.1.5..1.1.0.1..1.0.0.1..0.1.1.0..2.2.0.2..8.0.0.8
------
.....3........4........0........2........2........0........3........7...
....0.1......0.1......0.2......2.0......0.1......0.1......2.0......0.0..
...1.1.0....1.1.0....2.0.0....0.1.2....1.3.0....1.5.0....0.0.2....0.0.0.
..3.0.1.3..4.0.1.4..0.0.2.0..2.2.0.2..2.0.1.2..0.0.1.0..3.2.0.3..7.0.0.7

Crossrefs

Sequence in context: A003565 A238105 A363872 * A248312 A329653 A170874

Adjacent sequences: A166200 A166201 A166202 * A166204 A166205 A166206

Keyword

nonn

Author

R. H. Hardin Oct 09 2009

Status

approved