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A155355 Number of ways to place zero or more nonadjacent 1,1 2,1 2,2 3,0 3,1 3,2 3,3 4,1 polyhexes in any orientation on a planar nXnXn triangular grid. 0
1, 4, 13, 28, 49, 171, 1310, 8460, 42491, 242978, 2107793, 27648766, 373047925, 4984501036, 77677934468, 1580716536075, 41780194476260 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,2

COMMENTS

Same series for 1,1 2,1 3,0 3,1 3,2 3,3 4,1 polyhexes.

LINKS

Table of n, a(n) for n=4..20.

EXAMPLE

Maximal 9 X 9 X 9 example

...........0

..........1.0

.........1.1.0

........1.1.1.1

.......0.0.0.1.0

......1.1.0.0.0.1

.....0.1.0.0.0.1.1

....0.1.1.0.1.1.1.1

...0.1.1.1.0.1.0.0.0

CROSSREFS

Sequence in context: A155392 A155435 A155371 * A155356 A060488 A054968

Adjacent sequences:  A155352 A155353 A155354 * A155356 A155357 A155358

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 22 2009

STATUS

approved

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Last modified December 4 13:15 EST 2021. Contains 349526 sequences. (Running on oeis4.)