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Search: id:A110907
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| A110907 |
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Number of points in the standard root system version of the D_3 (or f.c.c.) lattice having L_infinity norm n. |
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+0
2
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OFFSET
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0,2
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COMMENT
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This lattice consists of all points (x,y,z) where x,y,z are integers with an even sum.
The L_infinity norm of a vector is the largest component in absolute value.
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REFERENCES
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J. H. Conway and N. J. A. Sloane, Sphere Packings, Lattices and Groups, Springer-Verlag, Chap. 4.
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LINKS
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G. Nebe and N. J. A. Sloane, Home page for this lattice
Index entries for sequences related to f.c.c. lattice
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EXAMPLE
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a(0) = 1: 000
a(1) = 12: +-1 +-1 0, where the 0 can be in any of the three coordinates
a(2) = 50: +-2 0 0 (6), +-2 +-1 +-1 (24), +-2 +-2 0 (12), +-2 +-2 +-2 (8).
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CROSSREFS
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Cf. A117216, A022144, A010014.
Sequence in context: A081292 A052021 A052022 this_sequence A009937 A009932 A009933
Adjacent sequences: A110904 A110905 A110906 this_sequence A110908 A110909 A110910
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KEYWORD
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nonn,easy,more
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AUTHOR
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njas, Apr 15 2008
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EXTENSIONS
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I would like to get analogous sequences for A_2, A_4, A_5, ..., D_4 (see A117216), D_5, ..., E_6, E_7, E_8.
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