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A135522
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a(n) = 2*a(n-1) + 3*a(n-2), with a(0) = 2 and a(1) = 3.
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15
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2, 3, 12, 33, 102, 303, 912, 2733, 8202, 24603, 73812, 221433, 664302, 1992903, 5978712, 17936133, 53808402, 161425203, 484275612, 1452826833, 4358480502, 13075441503, 39226324512, 117678973533, 353036920602, 1059110761803
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OFFSET
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0,1
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COMMENTS
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LINKS
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FORMULA
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O.g.f.: (5/(1-3*x) + 3/(1+x))/4.
a(n) = (5*3^n + 3*(-1)^n)/4. (End)
E.g.f.: (1/4)*(5*exp(3*x) + 3*exp(-x)). - G. C. Greubel, Oct 17 2016
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MATHEMATICA
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Transpose[NestList[Join[Rest[#], ListCorrelate[{3, 2}, #]]&, {2, 3}, 30]][[1]] (* Harvey P. Dale, Mar 14 2011 *)
CoefficientList[Series[(x-2)/(3x^2+2x-1), {x, 0, 30}], x] (* Harvey P. Dale, Mar 14 2011 *)
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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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