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A006778
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Number of n-step spirals on hexagonal lattice.
(Formerly M2652)
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0
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1, 3, 7, 15, 31, 59, 110, 198, 347, 592, 997, 1641, 2666, 4266, 6741, 10525, 16268, 24882, 37717, 56683, 84504, 125031, 183716, 268125, 388873, 560647, 803723, 1146013, 1625731
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OFFSET
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1,2
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COMMENTS
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The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
G. Szekeres and A. J. Guttmann, Spiral self-avoiding walks on the triangular lattice, J. Phys. A 20 (1987), 481-493.
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LINKS
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Table of n, a(n) for n=1..29.
G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2
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CROSSREFS
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Sequence in context: A229006 A023424 A276647 * A007574 A034480 A218281
Adjacent sequences: A006775 A006776 A006777 * A006779 A006780 A006781
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KEYWORD
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nonn,more
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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