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A309982 Number of counterclockwise n-step 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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
The hexagonal lattice is the familiar 2-dimensional 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
G. Szekeres and A. J. Guttmann, Spiral self-avoiding walks on the triangular lattice, J. Phys. A 20 (1987), 481-493.
CROSSREFS
Cf. A006776 (Model III).
Sequence in context: A299026 A007800 A362063 * A102726 A188900 A189075
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Aug 26 2019
STATUS
approved

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Last modified February 21 12:33 EST 2024. Contains 370235 sequences. (Running on oeis4.)