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A366662
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Sum of the divisors of 9^n-1.
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12
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15, 186, 1680, 15876, 123690, 1541568, 8992680, 111757968, 967814400, 9366647892, 62424587520, 852903426816, 4766016364260, 55176998178240, 550081165885440, 4829754617483040, 31725040326819840, 471309320999516160, 2535353780263288800, 33995669076586206864
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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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EXAMPLE
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a(2)=186 because 9^2-1 has divisors {1, 2, 4, 5, 8, 10, 16, 20, 40, 80}.
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MAPLE
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a:=n->numtheory[sigma](9^n-1):
seq(a(n), n=1..30);
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MATHEMATICA
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DivisorSigma[1, 9^Range[30]-1]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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