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A340864
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Numbers k such that both sigma_{-1}(k) > 2 and sigma_0(k)/sigma_{-1}(k) are integers.
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1
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672, 30240, 32760, 2178540, 23569920, 45532800, 142990848, 459818240, 1379454720, 14182439040, 43861478400, 51001180160, 66433720320, 153003540480, 403031236608, 704575228896, 13661860101120, 181742883469056, 6088728021160320, 14942123276641920, 20158185857531904
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(1) = 672 is the smallest number k that is both an Ore number and multiperfect such that sigma(k)/k > 2.
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MATHEMATICA
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Module[{a166069 = {120, 672, 30240, 32760, 523776, 2178540, 23569920, 45532800, 142990848, 459818240, 1379454720}, i, n, result = {}}, For[i = 1, i <= Length[a166069], i++, n = a166069[[i]]; If[Mod[DivisorSigma[0, n], DivisorSigma[-1, n]] == 0, AppendTo[result, n]]]; result]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Name changed by and more terms from Jinyuan Wang, Feb 11 2021
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STATUS
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approved
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