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A221209
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Decimal expansion of two times the Catalan constant.
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2
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1, 8, 3, 1, 9, 3, 1, 1, 8, 8, 3, 5, 4, 4, 3, 8, 0, 3, 0, 1, 0, 9, 2, 0, 7, 0, 2, 9, 8, 6, 4, 7, 6, 8, 2, 2, 1, 5, 4, 8, 2, 9, 8, 7, 4, 8, 5, 6, 3, 3, 4, 4, 2, 6, 8, 5, 3, 2, 9, 9, 6, 2, 3, 9, 2, 4, 3, 5, 2, 6, 0, 3, 9, 5, 5, 2, 5, 0, 9, 5, 3, 8, 9, 5, 8, 7, 1, 3, 0, 2, 5, 8, 5, 2, 2, 3, 0, 2, 1, 2
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OFFSET
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1,2
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REFERENCES
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I.S. Gradshteyn and I.M. Ryzhik, Table of integrals, series and products, 5th edition, Academic Press, 1994, eq. (3.521.2).
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LINKS
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FORMULA
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Equals Integral_{x=0..oo} x/cosh(x) dx.
Equals Integral_{x=0..Pi/2} x/sin(x) dx.
Equals 1 + Integral_{x=0..oo} x * exp(-x) * tanh(x) dx. (End)
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EXAMPLE
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1.83193118835443803010920702986476822154...
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MAPLE
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evalf(2*Catalan) ;
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MATHEMATICA
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PROG
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(PARI) default(realprecision, 100); 2*Catalan \\ G. C. Greubel, Aug 25 2018
(Magma) SetDefaultRealField(RealField(100)); R:=RealField(); 2*Catalan(R); // G. C. Greubel, Aug 25 2018
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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