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A083222
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a(n) = (4*5^n + (-5)^n)/5.
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5
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1, 3, 25, 75, 625, 1875, 15625, 46875, 390625, 1171875, 9765625, 29296875, 244140625, 732421875, 6103515625, 18310546875, 152587890625, 457763671875, 3814697265625, 11444091796875, 95367431640625, 286102294921875
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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) = (4*5^n + (-5)^n)/5.
G.f.: (1+3*x)/((1+5*x)(1-5*x)).
E.g.f.: (4*exp(5*x) + exp(-5*x))/5.
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MATHEMATICA
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LinearRecurrence[{0, 25}, {1, 3}, 30] (* or *) Riffle[NestList[25#&, 1, 10], NestList[ 25#&, 3, 10]] (* Harvey P. Dale, Dec 14 2017 *)
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PROG
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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