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A168376
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a(n) = (14*n - 7*(-1)^n - 9)/4.
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2
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3, 3, 10, 10, 17, 17, 24, 24, 31, 31, 38, 38, 45, 45, 52, 52, 59, 59, 66, 66, 73, 73, 80, 80, 87, 87, 94, 94, 101, 101, 108, 108, 115, 115, 122, 122, 129, 129, 136, 136, 143, 143, 150, 150, 157, 157, 164, 164, 171, 171, 178, 178, 185, 185, 192, 192, 199, 199, 206
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = 7*n - a(n-1) - 8, with n>1, a(1)=3.
G.f.: x*(3 + 4*x^2)/((1+x) * (x-1)^2). - R. J. Mathar, Nov 25 2009
E.g.f.: (1/4)*(-7 + 16*exp(x) + (14*x - 9)*exp(2*x))*exp(-x).
a(n) = a(n-1) + a(n-2) - a(n-3). (End)
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MATHEMATICA
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Table[7 n/2 - (7 (-1)^n + 9)/4, {n, 60}] (* Bruno Berselli, Sep 17 2013 *)
CoefficientList[Series[(3 + 4 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 17 2013 *)
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PROG
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(Magma) [n eq 1 select 3 else 7*n-Self(n-1)-8: n in [1..70]]; // Vincenzo Librandi, Sep 17 2013
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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Definition rewritten using Mathar's formula by Bruno Berselli, Sep 17 2013
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STATUS
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approved
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