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A168571
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a(n) = 25*(5^n - 1)/4.
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2
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0, 25, 150, 775, 3900, 19525, 97650, 488275, 2441400, 12207025, 61035150, 305175775, 1525878900, 7629394525, 38146972650, 190734863275, 953674316400, 4768371582025, 23841857910150, 119209289550775, 596046447753900, 2980232238769525
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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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a(n) = +6*a(n-1) -5*a(n-2).
G.f.: 25*x / ( (5*x-1)*(x-1) ). (End)
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MATHEMATICA
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CoefficientList[Series[25 x / ((1 - x) (1 - 5 x)), {x, 0, 30}], x] (* Vincenzo Librandi, Sep 24 2014 *)
LinearRecurrence[{6, -5}, {0, 25}, 25] (* G. C. Greubel, Jul 26 2016 *)
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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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