A166197 Number of nXnXn triangular nonnegative integer arrays, symmetric under 120 degree rotation, with all sums of an element and its neighbors <= 2.

1, 3, 1, 2, 6, 12, 26, 90, 200, 665, 3980, 10515, 52518, 433447, 1973317, 14252749, 166762668, 1065468116, 11148385916, 193707228525, 1758897674635, 26740845738267, 672553810724428, 9032785397690122, 199494539604910376

Offset

0,2

Links

R. H. Hardin, Table of n, a(n) for n=0..27

Example

All solutions for n=4
.....0........1........1........0........2........0...
....0.0......0.0......0.0......0.0......0.0......0.0..
...0.2.0....0.0.0....0.1.0....0.0.0....0.0.0....0.1.0.
..0.0.0.0..1.0.0.1..1.0.0.1..0.0.0.0..2.0.0.2..0.0.0.0

Crossrefs

Sequence in context: A201655 A049917 A308709 * A010279 A024743 A024963

Adjacent sequences: A166194 A166195 A166196 * A166198 A166199 A166200

Keyword

nonn

Author

R. H. Hardin, Oct 09 2009

Status

approved