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A168379
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a(n) = 4*n - 2*(-1)^n + 1.
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2
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7, 7, 15, 15, 23, 23, 31, 31, 39, 39, 47, 47, 55, 55, 63, 63, 71, 71, 79, 79, 87, 87, 95, 95, 103, 103, 111, 111, 119, 119, 127, 127, 135, 135, 143, 143, 151, 151, 159, 159, 167, 167, 175, 175, 183, 183, 191, 191, 199, 199, 207, 207, 215, 215, 223, 223, 231, 231
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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) = 8*n - a(n-1) - 2, with n>1, a(1)=7.
E.g.f.: (-2 + exp(x) + (4*x + 1)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 19 2016
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MAPLE
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MATHEMATICA
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CoefficientList[Series[(7 + x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 18 2013 *)
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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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