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A125962
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Numbers whose base-9 representation is 555555555......5.
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0
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0, 5, 50, 455, 4100, 36905, 332150, 2989355, 26904200, 242137805, 2179240250, 19613162255, 176518460300, 1588666142705, 14297995284350, 128681957559155, 1158137618032400, 10423238562291605, 93809147060624450, 844282323545620055, 7598540911910580500
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OFFSET
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0,2
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LINKS
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Table of n, a(n) for n=0..20.
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FORMULA
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a(n) = (9^n - 1)*5/8.
a(n) = 9*a(n-1) + 5 with n > 0, a(0)=0. - Vincenzo Librandi, Sep 30 2010
From Chai Wah Wu, Mar 12 2018: (Start)
a(n) = 10*a(n-1) - 9*a(n-2) for n > 1.
G.f.: 5*x/((1 - x)*(1 - 9*x)). (End)
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MATHEMATICA
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FromDigits[#, 9]&/@ Table[PadRight[{5}, n, 5], {n, 0, 20}] (* Harvey P. Dale, Jan 27 2011 *)
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PROG
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(PARI) a(n) = (9^n-1)*5/8; \\ Altug Alkan, Mar 12 2018
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CROSSREFS
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Sequence in context: A133646 A043032 A247771 * A361555 A266028 A228751
Adjacent sequences: A125959 A125960 A125961 * A125963 A125964 A125965
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KEYWORD
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nonn,easy
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AUTHOR
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Zerinvary Lajos, Feb 03 2007
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STATUS
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approved
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