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A168392
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a(n) = 5 + 8*floor((n-1)/2).
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2
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5, 5, 13, 13, 21, 21, 29, 29, 37, 37, 45, 45, 53, 53, 61, 61, 69, 69, 77, 77, 85, 85, 93, 93, 101, 101, 109, 109, 117, 117, 125, 125, 133, 133, 141, 141, 149, 149, 157, 157, 165, 165, 173, 173, 181, 181, 189, 189, 197, 197, 205, 205, 213, 213, 221, 221, 229, 229
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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) - 6 with n>1, a(1)=5.
a(1) = 5, a(2)=5, a(3)=13; for n>3, a(n) = a(n-1) +a(n-2) -a(n-3). - Harvey P. Dale, Jan 27 2013
E.g.f.: (-2 + 3*exp(x) + (4*x - 1)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 19 2016
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MATHEMATICA
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RecurrenceTable[{a[1]==5, a[n]==8n-a[n-1]-6}, a, {n, 80}] (* or *) LinearRecurrence[{1, 1, -1}, {5, 5, 13}, 80] (* or *) With[{c= LinearRecurrence[ {2, -1}, {5, 13}, 40]}, Riffle[c, c]] (* Harvey P. Dale, Jan 27 2013 *)
Table[5 + 8 Floor[(n - 1)/2], {n, 60}] (* Bruno Berselli, Sep 18 2013 *)
CoefficientList[Series[(5 + 3 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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