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A007589
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Dodecahedral surface numbers: a(0)=0, a(1)=1, a(2)=20, thereafter 2*((3*n-7)^2 +21).
(Formerly M5083)
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1
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0, 1, 20, 50, 92, 170, 284, 434, 620, 842, 1100, 1394, 1724, 2090, 2492, 2930, 3404, 3914, 4460, 5042, 5660, 6314, 7004, 7730, 8492, 9290, 10124, 10994, 11900, 12842, 13820, 14834, 15884, 16970, 18092, 19250
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OFFSET
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0,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
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a(n) = Vertices + Edges*(n-2) + Faces*facenumber(n-3) = 20 + 30(n-2) + 12*A000326(n-3) - Mitch Harris, Oct 25 2006
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MATHEMATICA
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Join[{0, 1, 20}, 2((3Range[3, 40]-7)^2+21)] (* From Harvey P. Dale, Sep 24 2011 *)
Join[{0, 1, 20}, CoefficientList[Series[2*(25-29*x+22*x^2)/(1-x)^3, {x, 0, 50}], x] ] (* Vincenzo Librandi, Jul 07 2012 *)
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PROG
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(MAGMA) I:=[0, 1, 20, 50, 92, 170]; [n le 6 select I[n] else 3*Self(n-1)-3*Self(n-2)+Self(n-3): n in [1..50]]; // Vincenzo Librandi, Jul 07 2012
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CROSSREFS
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Sequence in context: A177725 A053245 A115882 * A182462 A049390 A220040
Adjacent sequences: A007586 A007587 A007588 * A007590 A007591 A007592
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane, R. K. Guy.
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EXTENSIONS
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Revised definition - N. J. A. Sloane, Sep 25 2011
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STATUS
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approved
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