A155417 Number of ways to place zero or more nonadjacent 0,0 1,0 2,1 3,1 3,2 4,2 5,3 6,3 polyhexes in any orientation on a planar nXnXn triangular grid.

1, 7, 19, 37, 103, 427, 2227, 11583, 57485, 387397, 3244887, 30976146, 318914841

Offset

6,2

Links

Table of n, a(n) for n=6..18.

Example

Maximal 11 X 11 X 11 example
.............0
............0.0
...........0.0.0
..........0.0.0.1
.........0.1.1.1.0
........1.1.1.0.0.0
.......1.0.0.0.0.0.0
......0.0.0.1.0.0.1.1
.....0.1.1.1.0.1.1.0.0
....1.1.1.0.0.1.1.0.0.0
...1.0.0.0.1.1.0.0.0.0.0

Crossrefs

Sequence in context: A155299 A155379 A155243 * A155416 A155391 A155400

Adjacent sequences: A155414 A155415 A155416 * A155418 A155419 A155420

Keyword

nonn

Author

R. H. Hardin Jan 22 2009

Status

approved