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A199935
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Size (b^3_n) of unit sphere in a certain graph (see Hazama article for precise definition).
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1
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0, 0, 2, 5, 9, 14, 22, 36, 60, 99, 161, 260, 420, 680, 1102, 1785, 2889, 4674, 7562, 12236, 19800, 32039, 51841, 83880, 135720, 219600, 355322, 574925, 930249, 1505174, 2435422, 3940596, 6376020, 10316619, 16692641, 27009260, 43701900, 70711160, 114413062, 185124225
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OFFSET
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2,3
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 2..1000
Fumio Hazama, Spectra of graphs attached to the space of melodies, Discr. Math., 311 (2011), 2368-2383. See Table 2.1.
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1,1,-1).
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FORMULA
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a(n) = 2*A130578(n-1)-A130578(n-2).
G.f. -x^4*(-2+x) / ( (x-1)*(x^2-x+1)*(x^2+x-1) ). - R. J. Mathar, Nov 15 2011
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MATHEMATICA
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CoefficientList[Series[-x^2*(-2+x)/((x-1)*(x^2-x+1)*(x^2+x-1)), {x, 0, 50}], x] (* Vincenzo Librandi, Jul 10 2012 *)
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CROSSREFS
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Sequence in context: A011905 A098065 A123690 * A090937 A071609 A068501
Adjacent sequences: A199932 A199933 A199934 * A199936 A199937 A199938
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane, Nov 12 2011
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STATUS
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approved
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