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 | | http://functions.wolfram.com/04.23.26.0001.01 | 
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 | | BellB[n] == Sum[StirlingS2[n, k], {k, 0, n}] /; Element[n, Integers] && n >= 0 | 
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 | | Cell[BoxData[RowBox[List[RowBox[List[RowBox[List["BellB", "[", "n", "]"]], "\[Equal]", RowBox[List[UnderoverscriptBox["\[Sum]", RowBox[List["k", "=", "0"]], "n"], RowBox[List["StirlingS2", "[", 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>  <msub>  <semantics>  <mi> B </mi>  <annotation encoding='Mathematica'> TagBox["B", BellB] </annotation>  </semantics>  <mi> n </mi>  </msub>  <mo>  </mo>  <mrow>  <munderover>  <mo> ∑ </mo>  <mrow>  <mi> k </mi>  <mo> = </mo>  <mn> 0 </mn>  </mrow>  <mi> n </mi>  </munderover>  <msubsup>  <semantics>  <mi> 𝒮 </mi>  <annotation encoding='Mathematica'> TagBox["\[ScriptCapitalS]", StirlingS2] </annotation>  </semantics>  <mi> n </mi>  <mrow>  <mo> ( </mo>  <mi> k </mi>  <mo> ) </mo>  </mrow>  </msubsup>  </mrow>  </mrow>  <mo> /; </mo>  <mrow>  <mi> n </mi>  <mo> ∈ </mo>  <semantics>  <mi> ℕ </mi>  <annotation encoding='Mathematica'> TagBox["\[DoubleStruckCapitalN]", Function[Integers]] </annotation>  </semantics>  </mrow>  </mrow>  <annotation-xml encoding='MathML-Content'>  <apply>  <ci> Condition </ci>  <apply>  <eq />  <apply>  <ci> BellB </ci>  <ci> n </ci>  </apply>  <apply>  <sum />  <bvar>  <ci> k </ci>  </bvar>  <lowlimit>  <cn type='integer'> 0 </cn>  </lowlimit>  <uplimit>  <ci> n </ci>  </uplimit>  <apply>  <ci> StirlingS2 </ci>  <ci> n </ci>  <ci> k </ci>  </apply>  </apply>  </apply>  <apply>  <in />  <ci> n </ci>  <integers />  </apply>  </apply>  </annotation-xml>  </semantics>  </math> 
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 | | Cell[BoxData[RowBox[List[RowBox[List["HoldPattern", "[", RowBox[List["BellB", "[", "n_", "]"]], "]"]], "\[RuleDelayed]", RowBox[List[RowBox[List[UnderoverscriptBox["\[Sum]", RowBox[List["k", "=", "0"]], "n"], RowBox[List["StirlingS2", "[", RowBox[List["n", ",", "k"]], "]"]]]], "/;", 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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