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   http://functions.wolfram.com/06.26.20.0005.01
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    D[Erf[Subscript[z, 1], Subscript[z, 2]], {Subscript[z, 1], n}] == 
  Erf[Subscript[z, 1], Subscript[z, 2]] KroneckerDelta[n] - 
   Boole[n != 0, (((n - 1)!/(2^n Sqrt[Pi])) 
      Sum[((-1)^(k - 1) 2^(2 k) Subscript[z, 1]^(2 k - n - 1))/
        ((2 k - n - 1)! (n - k)!), {k, 1, n}])/E^Subscript[z, 1]^2] /; 
 Element[n, Integers] && n >= 0 
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   Cell[BoxData[RowBox[List[RowBox[List[RowBox[List[SubscriptBox["\[PartialD]", RowBox[List["{", RowBox[List[SubscriptBox["z", "1"], ",", "n"]], "}"]]], RowBox[List["Erf", "[", RowBox[List[SubscriptBox["z", "1"], ",", SubscriptBox["z", "2"]]], "]"]]]], "\[Equal]", RowBox[List[RowBox[List[RowBox[List["Erf", "[", RowBox[List[SubscriptBox["z", "1"], ",", SubscriptBox["z", "2"]]], "]"]], RowBox[List["KroneckerDelta", "[", "n", "]"]]]], "-", RowBox[List["Boole", "[", RowBox[List[RowBox[List["n", "\[NotEqual]", "0"]], ",", RowBox[List[FractionBox[RowBox[List[SuperscriptBox["2", RowBox[List["-", "n"]]], RowBox[List[RowBox[List["(", RowBox[List["n", "-", "1"]], ")"]], "!"]]]], SqrtBox["\[Pi]"]], SuperscriptBox["\[ExponentialE]", RowBox[List["-", SubsuperscriptBox["z", "1", "2"]]]], " ", RowBox[List[UnderoverscriptBox["\[Sum]", RowBox[List["k", "=", "1"]], "n"], FractionBox[RowBox[List[SuperscriptBox[RowBox[List["(", RowBox[List["-", "1"]], ")"]], RowBox[List["k", "-", "1"]]], SuperscriptBox["2", RowBox[List["2", " ", "k"]]], " ", SubsuperscriptBox["z", "1", RowBox[List[RowBox[List["2", "k"]], "-", "n", "-", "1"]]]]], RowBox[List[RowBox[List[RowBox[List["(", RowBox[List[RowBox[List["2", " ", "k"]], "-", "n", "-", "1"]], ")"]], "!"]], " ", RowBox[List[RowBox[List["(", RowBox[List["n", "-", "k"]], ")"]], "!"]]]]]]]]]]], "]"]]]]]], "/;", RowBox[List[RowBox[List["n", "\[Element]", "Integers"]], "\[And]", RowBox[List["n", "\[GreaterEqual]", "0"]]]]]]]] 
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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>  <mfrac>  <mrow>  <msup>  <mo> ∂ </mo>  <mi> n </mi>  </msup>  <mrow>  <mi> erf </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mrow>  <msub>  <mi> z </mi>  <mn> 1 </mn>  </msub>  <mo> , </mo>  <msub>  <mi> z </mi>  <mn> 2 </mn>  </msub>  </mrow>  <mo> ) </mo>  </mrow>  </mrow>  <mrow>  <mo> ∂ </mo>  <msubsup>  <mi> z </mi>  <mn> 1 </mn>  <mi> n </mi>  </msubsup>  </mrow>  </mfrac>  <mo> ⩵ </mo>  <mrow>  <mrow>  <mrow>  <mi> erf </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mrow>  <msub>  <mi> z </mi>  <mn> 1 </mn>  </msub>  <mo> , </mo>  <msub>  <mi> z </mi>  <mn> 2 </mn>  </msub>  </mrow>  <mo> ) </mo>  </mrow>  <mo> ⁢ </mo>  <msub>  <semantics>  <mi> δ </mi>  <annotation-xml encoding='MathML-Content'>  <ci> KroneckerDelta </ci>  </annotation-xml>  </semantics>  <mi> n </mi>  </msub>  </mrow>  <mo> - </mo>  <mrow>  <mi> Boole </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mrow>  <mrow>  <mi> n </mi>  <mo> ≠ </mo>  <mn> 0 </mn>  </mrow>  <mo> , </mo>  <mrow>  <mfrac>  <mrow>  <msup>  <mn> 2 </mn>  <mrow>  <mo> - </mo>  <mi> n </mi>  </mrow>  </msup>  <mo> ⁢ </mo>  <mrow>  <mrow>  <mo> ( </mo>  <mrow>  <mi> n </mi>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  <mo> ) </mo>  </mrow>  <mo> ! </mo>  </mrow>  </mrow>  <msqrt>  <mi> π </mi>  </msqrt>  </mfrac>  <mo> ⁢ </mo>  <msup>  <mi> ⅇ </mi>  <mrow>  <mo> - </mo>  <msubsup>  <mi> z </mi>  <mn> 1 </mn>  <mn> 2 </mn>  </msubsup>  </mrow>  </msup>  <mo> ⁢ </mo>  <mrow>  <munderover>  <mo> ∑ </mo>  <mrow>  <mi> k </mi>  <mo> = </mo>  <mn> 1 </mn>  </mrow>  <mi> n </mi>  </munderover>  <mfrac>  <mrow>  <msup>  <mrow>  <mo> ( </mo>  <mrow>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  <mo> ) </mo>  </mrow>  <mrow>  <mi> k </mi>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  </msup>  <mo> ⁢ </mo>  <msup>  <mn> 2 </mn>  <mrow>  <mn> 2 </mn>  <mo> ⁢ </mo>  <mi> k </mi>  </mrow>  </msup>  <mo> ⁢ </mo>  <msubsup>  <mi> z </mi>  <mn> 1 </mn>  <mrow>  <mrow>  <mn> 2 </mn>  <mo> ⁢ </mo>  <mi> k </mi>  </mrow>  <mo> - </mo>  <mi> n </mi>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  </msubsup>  </mrow>  <mrow>  <mrow>  <mrow>  <mo> ( </mo>  <mrow>  <mrow>  <mn> 2 </mn>  <mo> ⁢ </mo>  <mi> k </mi>  </mrow>  <mo> - </mo>  <mi> n </mi>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  <mo> ) </mo>  </mrow>  <mo> ! </mo>  </mrow>  <mo> ⁢ </mo>  <mrow>  <mrow>  <mo> ( </mo>  <mrow>  <mi> n </mi>  <mo> - </mo>  <mi> k </mi>  </mrow>  <mo> ) </mo>  </mrow>  <mo> ! </mo>  </mrow>  </mrow>  </mfrac>  </mrow>  </mrow>  </mrow>  <mo> ) </mo>  </mrow>  </mrow>  </mrow>  <mo> /; </mo>  <mrow>  <mi> n </mi>  <mo> ∈ </mo>  <mi> ℕ </mi>  </mrow>  </mrow>  <annotation-xml encoding='MathML-Content'>  <apply>  <ci> Condition </ci>  <apply>  <eq />  <apply>  <ci> D </ci>  <apply>  <ci> Erf </ci>  <apply>  <ci> Subscript </ci>  <ci> z </ci>  <cn type='integer'> 1 </cn>  </apply>  <apply>  <ci> Subscript </ci>  <ci> z </ci>  <cn type='integer'> 2 </cn>  </apply>  </apply>  <list>  <apply>  <ci> Subscript </ci>  <ci> z </ci>  <cn type='integer'> 1 </cn>  </apply>  <ci> n </ci>  </list>  </apply>  <apply>  <plus />  <apply>  <times />  <apply>  <ci> Erf </ci>  <apply>  <ci> Subscript </ci>  <ci> z </ci>  <cn type='integer'> 1 </cn>  </apply>  <apply>  <ci> Subscript </ci>  <ci> z </ci>  <cn type='integer'> 2 </cn>  </apply>  </apply>  <apply>  <ci> KroneckerDelta </ci>  <ci> n </ci>  </apply>  </apply>  <apply>  <times />  <cn type='integer'> -1 </cn>  <apply>  <ci> Boole </ci>  <apply>  <neq />  <ci> n </ci>  <cn type='integer'> 0 </cn>  </apply>  <apply>  <times />  <apply>  <times />  <apply>  <power />  <cn type='integer'> 2 </cn>  <apply>  <times />  <cn type='integer'> -1 </cn>  <ci> n </ci>  </apply>  </apply>  <apply>  <factorial />  <apply>  <plus />  <ci> n </ci>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <apply>  <power />  <apply>  <power />  <pi />  <cn type='rational'> 1 <sep /> 2 </cn>  </apply>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <apply>  <power />  <exponentiale />  <apply>  <times />  <cn type='integer'> -1 </cn>  <apply>  <power />  <apply>  <ci> Subscript </ci>  <ci> z </ci>  <cn type='integer'> 1 </cn>  </apply>  <cn type='integer'> 2 </cn>  </apply>  </apply>  </apply>  <apply>  <sum />  <bvar>  <ci> k </ci>  </bvar>  <lowlimit>  <cn type='integer'> 1 </cn>  </lowlimit>  <uplimit>  <ci> n </ci>  </uplimit>  <apply>  <times />  <apply>  <power />  <cn type='integer'> -1 </cn>  <apply>  <plus />  <ci> k </ci>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <apply>  <power />  <cn type='integer'> 2 </cn>  <apply>  <times />  <cn type='integer'> 2 </cn>  <ci> k </ci>  </apply>  </apply>  <apply>  <power />  <apply>  <ci> Subscript </ci>  <ci> z </ci>  <cn type='integer'> 1 </cn>  </apply>  <apply>  <plus />  <apply>  <times />  <cn type='integer'> 2 </cn>  <ci> k </ci>  </apply>  <apply>  <times />  <cn type='integer'> -1 </cn>  <ci> n </ci>  </apply>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <apply>  <power />  <apply>  <times />  <apply>  <factorial />  <apply>  <plus />  <apply>  <times />  <cn type='integer'> 2 </cn>  <ci> k </ci>  </apply>  <apply>  <times />  <cn type='integer'> -1 </cn>  <ci> n </ci>  </apply>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <apply>  <factorial />  <apply>  <plus />  <ci> n </ci>  <apply>  <times />  <cn type='integer'> -1 </cn>  <ci> k </ci>  </apply>  </apply>  </apply>  </apply>  <cn type='integer'> -1 </cn>  </apply>  </apply>  </apply>  </apply>  </apply>  </apply>  </apply>  </apply>  <apply>  <in />  <ci> n </ci>  <ci> ℕ </ci>  </apply>  </apply>  </annotation-xml>  </semantics>  </math> 
   
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  | Cell[BoxData[RowBox[List[RowBox[List["HoldPattern", "[", RowBox[List[SubscriptBox["\[PartialD]", RowBox[List[RowBox[List["{", RowBox[List[SubscriptBox["z_", "1"], ",", "n_"]], "}"]]]]], RowBox[List["Erf", "[", RowBox[List[SubscriptBox["z_", "1"], ",", SubscriptBox["z_", "2"]]], "]"]]]], "]"]], "\[RuleDelayed]", RowBox[List[RowBox[List[RowBox[List[RowBox[List["Erf", "[", RowBox[List[SubscriptBox["zz", "1"], ",", SubscriptBox["zz", "2"]]], "]"]], " ", RowBox[List["KroneckerDelta", "[", "n", "]"]]]], "-", RowBox[List["Boole", "[", RowBox[List[RowBox[List["n", "\[NotEqual]", "0"]], ",", FractionBox[RowBox[List[RowBox[List["(", RowBox[List[SuperscriptBox["2", RowBox[List["-", "n"]]], " ", RowBox[List[RowBox[List["(", RowBox[List["n", "-", "1"]], ")"]], "!"]]]], ")"]], " ", SuperscriptBox["\[ExponentialE]", RowBox[List["-", SubsuperscriptBox["zz", "1", "2"]]]], " ", RowBox[List[UnderoverscriptBox["\[Sum]", RowBox[List["k", "=", "1"]], "n"], FractionBox[RowBox[List[SuperscriptBox[RowBox[List["(", RowBox[List["-", "1"]], ")"]], RowBox[List["k", "-", "1"]]], " ", SuperscriptBox["2", RowBox[List["2", " ", "k"]]], " ", SubsuperscriptBox["zz", "1", RowBox[List[RowBox[List["2", " ", "k"]], "-", "n", "-", "1"]]]]], RowBox[List[RowBox[List[RowBox[List["(", RowBox[List[RowBox[List["2", " ", "k"]], "-", "n", "-", "1"]], ")"]], "!"]], " ", RowBox[List[RowBox[List["(", RowBox[List["n", "-", "k"]], ")"]], "!"]]]]]]]]], SqrtBox["\[Pi]"]]]], "]"]]]], "/;", RowBox[List[RowBox[List["n", "\[Element]", "Integers"]], "&&", RowBox[List["n", "\[GreaterEqual]", "0"]]]]]]]]]]  |  
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   Date Added to functions.wolfram.com (modification date)
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