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A035019
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Sizes of successive shells in hexagonal (or A_2) lattice.
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10
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1, 6, 6, 6, 12, 6, 6, 12, 6, 12, 12, 6, 6, 12, 12, 6, 12, 12, 12, 6, 18, 12, 12, 12, 12, 6, 12, 12, 6, 12, 12, 6, 12, 24, 12, 12, 6, 12, 6, 12, 12, 12, 12, 6, 12, 12, 12, 24, 12, 6, 18, 12, 12, 12, 12, 12, 18, 12, 12, 12, 12, 12, 12, 6, 12, 18, 12, 12, 12, 12
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OFFSET
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0,2
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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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J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 111.
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..10000
G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2
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FORMULA
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Nonzero coefficients in expansion of theta_3(q)*theta_3(q^3)+theta_2(q)*theta_2(q^3).
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CROSSREFS
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Cf. A004016.
Sequence in context: A179409 A186983 A046264 * A216057 A212096 A052380
Adjacent sequences: A035016 A035017 A035018 * A035020 A035021 A035022
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KEYWORD
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nonn,easy,nice
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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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