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A168458
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a(n) = 7 + 10*floor((n-1)/2).
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1
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7, 7, 17, 17, 27, 27, 37, 37, 47, 47, 57, 57, 67, 67, 77, 77, 87, 87, 97, 97, 107, 107, 117, 117, 127, 127, 137, 137, 147, 147, 157, 157, 167, 167, 177, 177, 187, 187, 197, 197, 207, 207, 217, 217, 227, 227, 237, 237, 247, 247, 257, 257, 267, 267, 277, 277, 287
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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) = 10*n - a(n-1) - 6, with n>1, a(1)=7.
a(n) = (10*n - 5*(-1)^n - 1)/2.
E.g.f.: (1/2)*(-5 + 6*exp(x) + (10*x - 1)*exp(2*x))*exp(-x). (End)
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MAPLE
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MATHEMATICA
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Table[7 + 10 Floor[(n - 1)/2], {n, 70}] (* or *) CoefficientList[Series[(7 + 3 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 19 2013 *)
LinearRecurrence[{1, 1, -1}, {7, 7, 17}, 60] (* Harvey P. Dale, Apr 12 2018 *)
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PROG
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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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STATUS
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approved
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