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A152218
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Numbers n such that sigma_2(n)*sigma_1(n)/sigma_0(n) is a perfect square.
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1
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1, 4, 529, 2116, 2583, 3249, 3346, 6150, 10332, 12474, 12792, 12996, 28224, 38240, 59245, 85905, 91035, 103607, 142560, 176382, 212949, 236980, 249744, 343620, 360096, 364140, 379050, 414428, 450840, 751530, 787710, 788424, 851796, 1059474, 1132096, 1366407
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OFFSET
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1,2
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LINKS
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FORMULA
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MATHEMATICA
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fQ[n_] := IntegerQ[ Sqrt[ DivisorSigma[2, n] DivisorSigma[1, n]/DivisorSigma[0, n]]]; k = 1; lst = {}; While[k < 1132096, If[ fQ@k, AppendTo[lst, k]; Print@k]; k++ ]; lst (* Robert G. Wilson v, Sep 10 2010 *)
Select[Range[137*10^4], IntegerQ[Sqrt[(DivisorSigma[2, #]DivisorSigma[ 1, #])/ DivisorSigma[ 0, #]]]&] (* Harvey P. Dale, Jun 18 2018 *)
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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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STATUS
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approved
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