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A006984
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Greatest minimal norm of sublattice of index n in hexagonal lattice.
(Formerly M2298)
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2
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1, 1, 3, 4, 3, 4, 7, 7, 9, 7, 7, 12, 13, 12, 13, 16, 13, 13, 19, 16, 21, 19, 19, 21, 25, 21, 27, 28, 21, 27, 31, 28, 27, 28, 31, 36, 37, 31, 39, 37, 37, 36, 43, 39, 39, 39, 39, 48, 49, 43, 43
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| 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
| N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| M. Bernstein, N. J. A. Sloane and P. E. Wright, On Sublattices of the Hexagonal Lattice, Discrete Math. 170 (1997) 29-39 (Abstract, pdf, ps).
G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2
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CROSSREFS
| Cf. A003051, A003050, A001615.
Sequence in context: A094151 A135800 A178152 * A087275 A072942 A025267
Adjacent sequences: A006981 A006982 A006983 * A006985 A006986 A006987
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KEYWORD
| nonn,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein (mira(AT)math.berkeley.edu)
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