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A347169
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Numbers k for which sigma(k)/k = 16/7.
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0
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OFFSET
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1,1
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COMMENTS
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This sequence will contain terms of the form 7*P, where P is a perfect number (A000396) not divisible by 7. Proof: sigma(7*P)/(7*P) = sigma(7)*sigma(P)/(7*P) = 8*(2*P)/(7*P) = 16/7. QED
Terms ending in "2" or "96" have this form. Example: a(n) = 7*A000396(n) for n = 1, 5, 6, 7, 8, 9 and a(n) = 7*A000396(n+1) for n = 2, 3.
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LINKS
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EXAMPLE
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544635 is a term, since sigma(544635)/544635 = 1244880/544635 = 16/7.
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MATHEMATICA
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Select[Range[5*10^8], DivisorSigma[1, #]/# == 16/7 &]
Do[If[DivisorSigma[1, k]/k == 16/7, Print[k]], {k, 5*10^8}]
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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