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 | | http://functions.wolfram.com/02.03.09.0015.01 | 
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 | | Pi == Limit[(2^(n + 1)/(2 - Subscript[b, 1])) ((Subscript[b, n]/2) 
     Sqrt[2 + Subscript[b, n - 1] Sqrt[2 + Subscript[b, n - 2] 
           Sqrt[2 + \[Ellipsis] + Subscript[b, 2] Sqrt[2 + 
                Sin[(Pi Subscript[b, 1])/4]]]]]), n -> Infinity] /; 
 Subscript[b, n] == 1 && Subscript[b, n - 1] == -1 && 
  (Subscript[b, k] == 1 && 2 <= k <= n - 2 && Element[k, Integers]) && 
  Element[Subscript[b, 1], Reals] && -2 <= Subscript[b, 1] <= 2 | 
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 | | Cell[BoxData[RowBox[List[RowBox[List["\[Pi]", "\[Equal]", RowBox[List["Limit", "[", RowBox[List[RowBox[List[FractionBox[SuperscriptBox["2", RowBox[List["n", "+", "1"]]], RowBox[List["2", "-", SubscriptBox["b", "1"]]]], RowBox[List["(", RowBox[List[FractionBox[SubscriptBox["b", "n"], "2"], " ", SqrtBox[RowBox[List["2", "+", RowBox[List[SubscriptBox["b", RowBox[List["n", "-", "1"]]], SqrtBox[RowBox[List["2", "+", RowBox[List[SubscriptBox["b", RowBox[List["n", "-", "2"]]], SqrtBox[RowBox[List["2", "+", "\[Ellipsis]", "+", " ", RowBox[List[SubscriptBox["b", "2"], SqrtBox[RowBox[List["2", "+", RowBox[List["Sin", "[", FractionBox[RowBox[List["\[Pi]", " ", SubscriptBox["b", "1"]]], "4"], "]"]]]]], " "]]]]], " "]]]]], " "]]]]]]], ")"]]]], ",", RowBox[List["n", "\[Rule]", "\[Infinity]"]]]], "]"]]]], "/;", "\[IndentingNewLine]", RowBox[List[RowBox[List[SubscriptBox["b", "n"], "\[Equal]", "1"]], "\[And]", RowBox[List[SubscriptBox["b", RowBox[List["n", "-", "1"]]], "\[Equal]", RowBox[List["-", "1"]]]], "\[And]", RowBox[List["(", RowBox[List[RowBox[List[SubscriptBox["b", "k"], "\[Equal]", "1"]], "\[And]", RowBox[List["2", "\[LessEqual]", "k", "\[LessEqual]", RowBox[List["n", "-", "2"]]]], "\[And]", RowBox[List["k", "\[Element]", "Integers"]]]], ")"]], "\[And]", RowBox[List[SubscriptBox["b", "1"], "\[Element]", "Reals"]], "\[And]", RowBox[List[RowBox[List["-", "2"]], "\[LessEqual]", SubscriptBox["b", "1"], "\[LessEqual]", "2"]]]]]]]] | 
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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>  <mi> π </mi>  <mo> ⩵ </mo>  <mrow>  <munder>  <mi> lim </mi>  <mrow>  <mi> n </mi>  <semantics>  <mo> → </mo>  <annotation encoding='Mathematica'> "\[Rule]" </annotation>  </semantics>  <mi> ∞ </mi>  </mrow>  </munder>  <mo> ⁢ </mo>  <mtext>   </mtext>  <mrow>  <mfrac>  <msup>  <mn> 2 </mn>  <mrow>  <mi> n </mi>  <mo> + </mo>  <mn> 1 </mn>  </mrow>  </msup>  <mrow>  <mn> 2 </mn>  <mo> - </mo>  <msub>  <mi> b </mi>  <mn> 1 </mn>  </msub>  </mrow>  </mfrac>  <mo> ⁢ </mo>  <mrow>  <mo> ( </mo>  <mrow>  <mfrac>  <msub>  <mi> b </mi>  <mi> n </mi>  </msub>  <mn> 2 </mn>  </mfrac>  <mo> ⁢ </mo>  <msqrt>  <mrow>  <mn> 2 </mn>  <mo> + </mo>  <mrow>  <msub>  <mi> b </mi>  <mrow>  <mi> n </mi>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  </msub>  <mo> ⁢ </mo>  <msqrt>  <mrow>  <mn> 2 </mn>  <mo> + </mo>  <mrow>  <msub>  <mi> b </mi>  <mrow>  <mi> n </mi>  <mo> - </mo>  <mn> 2 </mn>  </mrow>  </msub>  <mo> ⁢ </mo>  <msqrt>  <mrow>  <mn> 2 </mn>  <mo> + </mo>  <mo> … </mo>  <mo> + </mo>  <mtext>   </mtext>  <mrow>  <msub>  <mi> b </mi>  <mn> 2 </mn>  </msub>  <mo> ⁢ </mo>  <msqrt>  <mrow>  <mn> 2 </mn>  <mo> + </mo>  <mrow>  <mi> sin </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mfrac>  <mrow>  <mi> π </mi>  <mo> ⁢ </mo>  <msub>  <mi> b </mi>  <mn> 1 </mn>  </msub>  </mrow>  <mn> 4 </mn>  </mfrac>  <mo> ) </mo>  </mrow>  </mrow>  </msqrt>  <mtext>   </mtext>  </mrow>  </mrow>  </msqrt>  <mtext>   </mtext>  </mrow>  </mrow>  </msqrt>  <mtext>   </mtext>  </mrow>  </mrow>  </msqrt>  </mrow>  <mo> ) </mo>  </mrow>  </mrow>  </mrow>  </mrow>  <mo> /; </mo>  <mrow>  <mrow>  <msub>  <mi> b </mi>  <mi> n </mi>  </msub>  <mo> ⩵ </mo>  <mn> 1 </mn>  </mrow>  <mo> ∧ </mo>  <mrow>  <msub>  <mi> b </mi>  <mrow>  <mi> n </mi>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  </msub>  <mo> ⩵ </mo>  <mrow>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  </mrow>  <mo> ∧ </mo>  <mrow>  <mo> ( </mo>  <mrow>  <mrow>  <msub>  <mi> b </mi>  <mi> k </mi>  </msub>  <mo> ⩵ </mo>  <mn> 1 </mn>  </mrow>  <mo> ∧ </mo>  <mrow>  <mn> 2 </mn>  <mo> ≤ </mo>  <mi> k </mi>  <mo> ≤ </mo>  <mrow>  <mi> n </mi>  <mo> - </mo>  <mn> 2 </mn>  </mrow>  </mrow>  <mo> ∧ </mo>  <mrow>  <mi> k </mi>  <mo> ∈ </mo>  <mi> ℕ </mi>  </mrow>  </mrow>  <mo> ) </mo>  </mrow>  <mo> ∧ </mo>  <mrow>  <msub>  <mi> b </mi>  <mn> 1 </mn>  </msub>  <mo> ∈ </mo>  <semantics>  <mi> ℝ </mi>  <annotation encoding='Mathematica'> TagBox["\[DoubleStruckCapitalR]", Function[List[], Reals]] </annotation>  </semantics>  </mrow>  <mo> ∧ </mo>  <mrow>  <mrow>  <mo> - </mo>  <mn> 2 </mn>  </mrow>  <mo> ≤ </mo>  <msub>  <mi> b </mi>  <mn> 1 </mn>  </msub>  <mo> ≤ </mo>  <mn> 2 </mn>  </mrow>  </mrow>  </mrow>  <annotation-xml encoding='MathML-Content'>  <apply>  <ci> Condition </ci>  <apply>  <eq />  <pi />  <apply>  <limit />  <bvar>  <ci> n </ci>  </bvar>  <condition>  <apply>  <tendsto />  <ci> n </ci>  <infinity />  </apply>  </condition>  <apply>  <times />  <apply>  <times />  <apply>  <power />  <cn type='integer'> 2 </cn>  <apply>  <plus />  <ci> n </ci>  <cn type='integer'> 1 </cn>  </apply>  </apply>  <apply>  <power />  <apply>  <plus />  <cn type='integer'> 2 </cn>  <apply>  <times />  <cn type='integer'> -1 </cn>  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <cn type='integer'> 1 </cn>  </apply>  </apply>  </apply>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <apply>  <times />  <apply>  <times />  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <ci> n </ci>  </apply>  <apply>  <power />  <cn type='integer'> 2 </cn>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <apply>  <power />  <apply>  <plus />  <cn type='integer'> 2 </cn>  <apply>  <times />  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <apply>  <plus />  <ci> n </ci>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <apply>  <power />  <apply>  <plus />  <cn type='integer'> 2 </cn>  <apply>  <times />  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <apply>  <plus />  <ci> n </ci>  <cn type='integer'> -2 </cn>  </apply>  </apply>  <apply>  <power />  <apply>  <plus />  <cn type='integer'> 2 </cn>  <ci> … </ci>  <apply>  <times />  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <cn type='integer'> 2 </cn>  </apply>  <apply>  <power />  <apply>  <plus />  <cn type='integer'> 2 </cn>  <apply>  <sin />  <apply>  <times />  <pi />  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <cn type='integer'> 1 </cn>  </apply>  <apply>  <power />  <cn type='integer'> 4 </cn>  <cn type='integer'> -1 </cn>  </apply>  </apply>  </apply>  </apply>  <cn type='rational'> 1 <sep /> 2 </cn>  </apply>  </apply>  </apply>  <cn type='rational'> 1 <sep /> 2 </cn>  </apply>  </apply>  </apply>  <cn type='rational'> 1 <sep /> 2 </cn>  </apply>  </apply>  </apply>  <cn type='rational'> 1 <sep /> 2 </cn>  </apply>  </apply>  </apply>  </apply>  </apply>  <apply>  <and />  <apply>  <eq />  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <ci> n </ci>  </apply>  <cn type='integer'> 1 </cn>  </apply>  <apply>  <eq />  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <apply>  <plus />  <ci> n </ci>  <cn type='integer'> -1 </cn>  </apply>  </apply>  <cn type='integer'> -1 </cn>  </apply>  <apply>  <and />  <apply>  <eq />  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <ci> k </ci>  </apply>  <cn type='integer'> 1 </cn>  </apply>  <apply>  <leq />  <cn type='integer'> 2 </cn>  <ci> k </ci>  <apply>  <plus />  <ci> n </ci>  <cn type='integer'> -2 </cn>  </apply>  </apply>  <apply>  <in />  <ci> k </ci>  <ci> ℕ </ci>  </apply>  </apply>  <apply>  <in />  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <cn type='integer'> 1 </cn>  </apply>  <reals />  </apply>  <apply>  <leq />  <cn type='integer'> -2 </cn>  <apply>  <ci> Subscript </ci>  <ci> b </ci>  <cn type='integer'> 1 </cn>  </apply>  <cn type='integer'> 2 </cn>  </apply>  </apply>  </apply>  </annotation-xml>  </semantics>  </math> 
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 | | Cell[BoxData[RowBox[List[RowBox[List["HoldPattern", "[", "\[Pi]", "]"]], "\[RuleDelayed]", RowBox[List[RowBox[List["Limit", "[", RowBox[List[FractionBox[RowBox[List[SuperscriptBox["2", RowBox[List["n", "+", "1"]]], " ", RowBox[List["(", RowBox[List[SubscriptBox["b", "n"], " ", SqrtBox[RowBox[List["2", "+", RowBox[List[SubscriptBox["b", RowBox[List["n", "-", "1"]]], " ", SqrtBox[RowBox[List["2", "+", RowBox[List[SubscriptBox["b", RowBox[List["n", "-", "2"]]], " ", SqrtBox[RowBox[List["2", "+", "\[Ellipsis]", "+", RowBox[List[SubscriptBox["b", "2"], " ", SqrtBox[RowBox[List["2", "+", RowBox[List["Sin", "[", FractionBox[RowBox[List["\[Pi]", " ", SubscriptBox["b", "1"]]], "4"], "]"]]]]]]]]]]]]]]]]]]]]]], ")"]]]], RowBox[List[RowBox[List["(", RowBox[List["2", "-", SubscriptBox["b", "1"]]], ")"]], " ", "2"]]], ",", RowBox[List["n", "\[Rule]", "\[Infinity]"]]]], "]"]], "/;", RowBox[List[RowBox[List[SubscriptBox["b", "n"], "\[Equal]", "1"]], "&&", RowBox[List[SubscriptBox["b", RowBox[List["n", "-", "1"]]], "\[Equal]", RowBox[List["-", "1"]]]], "&&", RowBox[List["(", RowBox[List[RowBox[List[SubscriptBox["b", "k"], "\[Equal]", "1"]], "&&", RowBox[List["2", "\[LessEqual]", "k", "\[LessEqual]", RowBox[List["n", "-", "2"]]]], "&&", RowBox[List["k", "\[Element]", "Integers"]]]], ")"]], "&&", RowBox[List[SubscriptBox["b", "1"], "\[Element]", "Reals"]], "&&", RowBox[List[RowBox[List["-", "2"]], "\[LessEqual]", SubscriptBox["b", "1"], "\[LessEqual]", "2"]]]]]]]]]] | 
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 | |  L. D. Servi, "Nested Square Roots of 2", American Mathematical Monthly, v. 110, issue 4, pp. 326-329 (2003) | 
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 | | Date Added to functions.wolfram.com (modification date) | 
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