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Search: id:A035877
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| A035877 |
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Coordination sequence for diamond structure D^+_2. (Edges defined by l_1 norm = 1.) |
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1
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| 1, 2, 12, 6, 24, 10, 36, 14, 48, 18, 60, 22, 72, 26, 84, 30, 96, 34, 108, 38, 120, 42, 132, 46, 144, 50, 156, 54, 168, 58, 180, 62, 192, 66, 204, 70, 216, 74, 228, 78, 240
(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)a(n+3) = -24 + a(n+1)a(n+2).
G.f.: (1+2x+10x^2+2x^3+x^4)/(1-x^2)^2, and a(2n)=12n for n>0, a(2n+1)=4n+2.
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MAPLE
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A035877 := proc(m) local k, t1; t1 := 2*binomial((2+2*m)/2-1, 1); if m mod 2 = 0 then t1 := t1+add(2^k*binomial(2, k)*binomial(m-1, k-1), k=0..2); fi; t1; end;
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CROSSREFS
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Adjacent sequences: A035874 A035875 A035876 this_sequence A035878 A035879 A035880
Sequence in context: A112100 A015808 A079080 this_sequence A086494 A107414 A133437
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KEYWORD
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nonn
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AUTHOR
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J. Serra-Sagrista (jserra(AT)ccd.uab.es) Recomputed by njas Nov 27 1998.
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