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A109002
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Maximal difference between two n-digit numbers.
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6
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9, 89, 899, 8999, 89999, 899999, 8999999, 89999999, 899999999, 8999999999, 89999999999, 899999999999, 8999999999999, 89999999999999, 899999999999999
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = (10^n -1) - 10^(n-1), n > 1.
G.f.: 9*x - x^2*(-89+80*x) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Oct 29 2011
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EXAMPLE
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a(1) = 9 - 0 = 9, a(4) = 9999 - 1000 = 8999.
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MATHEMATICA
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Join[{9}, Table[FromDigits[PadRight[{8}, n, 9]], {n, 2, 20}]] (* or *) LinearRecurrence[{11, -10}, {9, 89, 899}, 20] (* Harvey P. Dale, May 09 2021 *)
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PROG
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CROSSREFS
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KEYWORD
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base,easy,nonn
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AUTHOR
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STATUS
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approved
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