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A168460
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a(n) = 6 + 10*floor((n-1)/2).
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1
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6, 6, 16, 16, 26, 26, 36, 36, 46, 46, 56, 56, 66, 66, 76, 76, 86, 86, 96, 96, 106, 106, 116, 116, 126, 126, 136, 136, 146, 146, 156, 156, 166, 166, 176, 176, 186, 186, 196, 196, 206, 206, 216, 216, 226, 226, 236, 236, 246, 246, 256, 256, 266, 266, 276, 276, 286
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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) - 8, with n>1, a(1)=6.
G.f.: 2*x*(3 + 2*x^2) / ( (1+x)*(x-1)^2 ). (End)
a(n) = (10*n - 5*(-1)^n - 3)/2.
E.g.f.: (1/2)*(-5 + 8*exp(x) + (10*x - 3)*exp(2*x))*exp(-x). (End)
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MAPLE
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MATHEMATICA
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RecurrenceTable[{a[1]==6, a[n]==10n-a[n-1]-8}, a, {n, 80}] (* or *) LinearRecurrence[{1, 1, -1}, {6, 6, 16}, 80] (* Harvey P. Dale, Apr 25 2011 *)
Table[6 + 10 Floor[(n - 1)/2], {n, 70}] (* or *) CoefficientList[Series[2 (3 + 2 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 19 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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