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A366603
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Sum of the divisors of 4^n-1.
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11
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4, 24, 104, 432, 1536, 8736, 22528, 111456, 473600, 1999872, 5909760, 38054016, 89522176, 462274560, 2015330304, 7304603328, 22907191296, 166290432000, 366506672128, 2220409884672, 7645340651520, 29833839544320, 95821839806976, 648494317126656
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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(4)=432 because 4^4-1 has divisors {1, 3, 5, 15, 17, 51, 85, 255}.
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MAPLE
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a:=n->numtheory[sigma](4^n-1):
seq(a(n), n=1..100);
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MATHEMATICA
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DivisorSigma[1, 4^Range[30]-1] (* Paolo Xausa, Oct 14 2023 *)
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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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