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   http://functions.wolfram.com/13.05.29.0023.01
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    DivisorSigma[1, n] <= HarmonicNumber[n] + Exp[HarmonicNumber[n]] 
    Log[HarmonicNumber[n]] /; Element[n, Integers] && n >= 1 
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   Cell[BoxData[RowBox[List[RowBox[List[RowBox[List["DivisorSigma", "[", RowBox[List["1", ",", "n"]], "]"]], "\[LessEqual]", RowBox[List[RowBox[List["HarmonicNumber", "[", "n", "]"]], "+", RowBox[List[RowBox[List["Exp", "[", RowBox[List["HarmonicNumber", "[", "n", "]"]], "]"]], RowBox[List["Log", "[", RowBox[List["HarmonicNumber", "[", "n", "]"]], "]"]]]]]]]], "/;", RowBox[List[RowBox[List["n", "\[Element]", "Integers"]], "\[And]", RowBox[List["n", "\[GreaterEqual]", "1"]]]]]]]] 
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   <math xmlns='http://www.w3.org/1998/Math/MathML' mathematica:form='TraditionalForm' xmlns:mathematica='http://www.wolfram.com/XML/'>  <semantics>  <mrow>  <mrow>  <mrow>  <msub>  <semantics>  <mi> σ </mi>  <annotation encoding='Mathematica'> TagBox["\[Sigma]", DivisorSigma] </annotation>  </semantics>  <mn> 1 </mn>  </msub>  <mo> ( </mo>  <mi> n </mi>  <mo> ) </mo>  </mrow>  <mo> ≤ </mo>  <mrow>  <msub>  <semantics>  <mi> H </mi>  <annotation-xml encoding='MathML-Content'>  <ci> HarmonicNumber </ci>  </annotation-xml>  </semantics>  <mi> n </mi>  </msub>  <mo> + </mo>  <mrow>  <msup>  <mi> ⅇ </mi>  <msub>  <semantics>  <mi> H </mi>  <annotation-xml encoding='MathML-Content'>  <ci> HarmonicNumber </ci>  </annotation-xml>  </semantics>  <mi> n </mi>  </msub>  </msup>  <mo> ⁢ </mo>  <mrow>  <mi> log </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <msub>  <semantics>  <mi> H </mi>  <annotation-xml encoding='MathML-Content'>  <ci> HarmonicNumber </ci>  </annotation-xml>  </semantics>  <mi> n </mi>  </msub>  <mo> ) </mo>  </mrow>  </mrow>  </mrow>  </mrow>  <mo> /; </mo>  <mrow>  <mi> n </mi>  <mo> ∈ </mo>  <msup>  <mi> ℕ </mi>  <mo> + </mo>  </msup>  </mrow>  </mrow>  <annotation-xml encoding='MathML-Content'>  <apply>  <ci> Condition </ci>  <apply>  <leq />  <apply>  <ci> DivisorSigma </ci>  <cn type='integer'> 1 </cn>  <ci> n </ci>  </apply>  <apply>  <plus />  <apply>  <ci> HarmonicNumber </ci>  <ci> n </ci>  </apply>  <apply>  <times />  <apply>  <power />  <exponentiale />  <apply>  <ci> HarmonicNumber </ci>  <ci> n </ci>  </apply>  </apply>  <apply>  <ln />  <apply>  <ci> HarmonicNumber </ci>  <ci> n </ci>  </apply>  </apply>  </apply>  </apply>  </apply>  <apply>  <in />  <ci> n </ci>  <apply>  <ci> SuperPlus </ci>  <ci> ℕ </ci>  </apply>  </apply>  </apply>  </annotation-xml>  </semantics>  </math> 
   
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  | Cell[BoxData[RowBox[List[RowBox[List[RowBox[List["DivisorSigma", "[", RowBox[List["1", ",", "n"]], "]"]], "\[LessEqual]", RowBox[List[RowBox[List["HarmonicNumber", "[", "n", "]"]], "+", RowBox[List[SuperscriptBox["\[ExponentialE]", RowBox[List["HarmonicNumber", "[", "n", "]"]]], " ", RowBox[List["Log", "[", RowBox[List["HarmonicNumber", "[", "n", "]"]], "]"]]]]]]]], "/;", RowBox[List[RowBox[List["n", "\[Element]", "Integers"]], "&&", RowBox[List["n", "\[GreaterEqual]", "1"]]]]]]]]  |  
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   Date Added to functions.wolfram.com (modification date)
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