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A168461
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a(n) = 10*floor(n/2).
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1
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0, 10, 10, 20, 20, 30, 30, 40, 40, 50, 50, 60, 60, 70, 70, 80, 80, 90, 90, 100, 100, 110, 110, 120, 120, 130, 130, 140, 140, 150, 150, 160, 160, 170, 170, 180, 180, 190, 190, 200, 200, 210, 210, 220, 220, 230, 230, 240, 240, 250, 250, 260, 260, 270, 270, 280
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = 10*n - a(n-1) - 10, with n>1, a(1)=0.
a(n) = (5/2)*(2*n + (-1)^n - 1).
E.g.f.: (5/2)*(1 +(2*x - 1)*exp(2*x))*exp(-x). (End)
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MAPLE
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MATHEMATICA
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Table[10 Floor[n/2], {n, 70}] (* or *) CoefficientList[Series[10 x/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 19 2013 *)
LinearRecurrence[{1, 1, -1}, {0, 10, 10}, 60] (* Harvey P. Dale, Mar 02 2024 *)
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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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