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A165351
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Numerator of 3*n/2.
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7
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0, 3, 3, 9, 6, 15, 9, 21, 12, 27, 15, 33, 18, 39, 21, 45, 24, 51, 27, 57, 30, 63, 33, 69, 36, 75, 39, 81, 42, 87, 45, 93, 48, 99, 51, 105, 54, 111, 57, 117, 60, 123, 63, 129, 66, 135, 69, 141, 72, 147, 75, 153, 78, 159, 81, 165, 84, 171, 87, 177, 90, 183, 93, 189, 96, 195
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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G.f.: 3*x*(1+x+x^2)/((1-x)^2 * (1+x)^2).
a(n) = 3*n*(3 - (-1)^n)/4.
E.g.f.: (3*x/2)*( 2*cosh(x) + sinh(x) ). (End)
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MAPLE
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MATHEMATICA
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CoefficientList[Series[3*x*(1+x+x^2)/(1-x^2)^2, {x, 0, 70}], x] (* Vincenzo Librandi, Mar 03 2014 *)
LinearRecurrence[{0, 2, 0, -1}, {0, 3, 3, 9}, 70] (* Harvey P. Dale, Jun 20 2021 *)
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PROG
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(SageMath) [3*n*(3-(-1)^n)/4 for n in (0..100)] # G. C. Greubel, Jul 31 2022
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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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