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A226508
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a(n) = Sum_{i=3^n..3^(n+1)-1} i.
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2
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3, 33, 315, 2889, 26163, 235953, 2125035, 19129689, 172180323, 1549662273, 13947078555, 125524061289, 1129717614483, 10167461718993, 91507165036875, 823564514029689, 7412080712360643, 66708726669526113, 600378540800575995, 5403406869529706889
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OFFSET
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0,1
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COMMENTS
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Partial sums give 3, 36, 351, 3240, 29403,...: A026121.
a(n) is the sum of all integers having n+1 digits in their ternary expansion (without leading zeros). - Jonathan Vos Post, Sep 07 2006
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LINKS
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FORMULA
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a(0)=3, a(1)=33, a(n)=12*a(n-1)-27*a(n-2). - Harvey P. Dale, Jun 19 2013
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EXAMPLE
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a(0) = 1+2 = 3,
a(1) = 3+4+5+6+7+8 = 33.
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MATHEMATICA
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Table[3^(n - 1) (4 3^(n + 1) - 3), {n, 0, 20}] (* Bruno Berselli, Jun 11 2013 *)
LinearRecurrence[{12, -27}, {3, 33}, 30] (* Harvey P. Dale, Jun 19 2013 *)
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PROG
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(PARI) a(n) = sum(i=3^n, 3^(n+1)-1, i) \\ Michel Marcus, Jun 11 2013
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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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STATUS
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approved
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