

A309982


Number of counterclockwise nstep spirals on hexagonal lattice where turns of 2*Pi/3 are forbidden.


3



1, 2, 4, 8, 16, 31, 60, 112, 207, 375, 667, 1173, 2026, 3466, 5846, 9770, 16138, 26441, 42893, 69073, 110309, 174972, 275554, 431286, 670782, 1037412, 1595412, 2440904, 3715497, 5628849, 8487944, 12743206, 19050110, 28362647, 42060657, 62137953, 91461095, 134144841, 196071213
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OFFSET

1,2


COMMENTS

The hexagonal lattice is the familiar 2dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.
Corresponds to Model II of the Szekeres and Guttmann paper.


LINKS



CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



