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A366634
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Sum of the divisors of 7^n-1.
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11
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12, 124, 780, 7812, 33624, 354640, 1704240, 18929096, 97036800, 800520192, 3958188480, 56928231360, 193778020824, 1830926384640, 11181115146240, 115997032277280, 465294239722800, 5175558387507200, 22852200371636160, 287850454432579584, 1318081737957660000
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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(5)=33624 because 7^5-1 has divisors {1, 2, 3, 6, 2801, 5602, 8403, 16806}.
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MAPLE
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a:=n->numtheory[sigma](7^n-1):
seq(a(n), n=1..100);
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MATHEMATICA
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DivisorSigma[1, 7^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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