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Search: id:A035601
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| A035601 |
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Number of points of L1 norm 7 in cubic lattice Z^n. |
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+0
2
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| 0, 2, 28, 198, 952, 3530, 10836, 28814, 68464, 148626, 299660, 568150, 1022760, 1761370, 2919620, 4680990, 7288544, 11058466, 16395516, 23810534, 33940120, 47568618, 65652532, 89347502, 120037968, 159369650, 209284972
(list; graph; listen)
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OFFSET
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0,2
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REFERENCES
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J. Serra-Sagrista, Enumeration of lattice points in l_1 norm, Information Processing Letters, 76, no. 1-2 (2000), 39-44.
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LINKS
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J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (Abstract, pdf, ps).
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FORMULA
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a(n)= ( 8*n^6 +4*5*7*n^4 +8*7*7*n^2 +2*5*9 )*n/(5*7*9). - frank.ellermann(AT)t-online.de, Mar 16 2002
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MAPLE
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f := proc(d, m) local i; sum( 2^i*binomial(d, i)*binomial(m-1, i-1), i=1..min(d, m)); end; # n=dimension, m=norm
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CROSSREFS
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Cf. A035596 - A035607.
Sequence in context: A065340 A001798 A123787 this_sequence A001759 A056261 A097353
Adjacent sequences: A035598 A035599 A035600 this_sequence A035602 A035603 A035604
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KEYWORD
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nonn,easy
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AUTHOR
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njas
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