A155274 Number of ways to place zero or more nonadjacent 1,1 2,1 3,0 3,1 3,2 4,3 polyhexes in any orientation on a planar nXnXn triangular grid.

1, 3, 9, 19, 33, 122, 733, 3984, 18507, 108272, 955732, 10449887, 117050472, 1441595909, 22302751858, 436682293027, 10013251106293, 259927601261214

Offset

4,2

Links

Table of n, a(n) for n=4..21.

Example

Maximal 13 X 13 X 13 example
...............0
..............0.1
.............0.1.0
............1.1.1.0
...........0.0.0.1.0
..........0.1.0.0.0.1
.........0.1.0.0.0.1.0
........1.1.1.0.1.1.1.0
.......0.0.0.1.0.0.0.1.0
......1.0.0.0.0.0.1.0.0.1
.....0.1.0.0.1.1.1.0.0.1.0
....0.1.1.1.0.0.1.0.1.1.1.0
...0.1.0.0.0.0.0.1.0.0.0.1.0

Crossrefs

Sequence in context: A146465 A147119 A146184 * A058058 A348308 A062748

Adjacent sequences: A155271 A155272 A155273 * A155275 A155276 A155277

Keyword

nonn

Author

R. H. Hardin Jan 22 2009

Status

approved