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A133486
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a(n) = Sum_{ k = 0 to n-1} ( subtract k modulo 9 from 9, multiply this by k-th power of 10 ).
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1
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9, 89, 789, 6789, 56789, 456789, 3456789, 23456789, 123456789, 9123456789, 89123456789, 789123456789, 6789123456789, 56789123456789, 456789123456789, 3456789123456789, 23456789123456789, 123456789123456789, 9123456789123456789, 89123456789123456789
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = sum(0 to n-1, ((9-(k % 9))*10^k) ).
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EXAMPLE
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a(6) = 9+80+700+6000+50000+400000 = 456789.
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MATHEMATICA
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Accumulate[Table[(9-Mod[n, 9])10^n, {n, 0, 20}]] (* or *) Table[FromDigits[PadLeft[ {}, n, Range[9]]], {n, 20}] (* Harvey P. Dale, May 08 2022 *)
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PROG
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(PARI) a(n) = sum(k=0, n-1, ((9-(k % 9))*10^k) ); \\ Michel Marcus, Aug 12 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Prashant Garg (prashant.garg1988(AT)yahoo.com), Nov 30 2007
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EXTENSIONS
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STATUS
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approved
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