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A019609
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Decimal expansion of Pi*e.
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39
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8, 5, 3, 9, 7, 3, 4, 2, 2, 2, 6, 7, 3, 5, 6, 7, 0, 6, 5, 4, 6, 3, 5, 5, 0, 8, 6, 9, 5, 4, 6, 5, 7, 4, 4, 9, 5, 0, 3, 4, 8, 8, 8, 5, 3, 5, 7, 6, 5, 1, 1, 4, 9, 6, 1, 8, 7, 9, 6, 0, 1, 1, 3, 0, 1, 7, 9, 2, 2, 8, 6, 1, 1, 1, 5, 7, 3, 3, 0, 8, 0, 7, 5, 7, 2, 5, 6, 3, 8, 6, 9, 7, 1, 0, 4, 7, 3, 9, 4
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OFFSET
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1,1
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COMMENTS
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Pi*e ~= 2*( Sum_{k>=1} (1/Product_{k=1..n}(2*k-1) ) + 725013737/1105744026 )^2. - Alexander R. Povolotsky, Aug 08 2009
Not known to be irrational (though of course conjectured transcendental), see e.g. Klee & Wagon. - Charles R Greathouse IV, Jul 23 2015
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REFERENCES
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Victor Klee and Stan Wagon, Old and New Unsolved Problems in Plane Geometry and Number Theory, Mathematical Association of America (1991). Problem 22, p. 243.
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LINKS
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FORMULA
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Limit_{k->oo} 4k/u(k)^2 where u(1)=0, u(2)=1, u(k+2) = u(k+1) + u(k)/(2k). - Benoit Cloitre, Aug 14 2003
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EXAMPLE
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8.53973422267356706546355086954657449503488853576511496187960113...
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MATHEMATICA
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PROG
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(PARI) default(realprecision, 20080); x=Pi*exp(1); for (n=1, 20000, d=floor(x); x=(x-d)*10; write("b019609.txt", n, " ", d)); \\ Harry J. Smith, Apr 27 2009
(Magma) SetDefaultRealField(RealField(100)); R:= RealField(); Pi(R)*Exp(1); // G. C. Greubel, Aug 24 2018
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CROSSREFS
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Cf. A159822 (continued fraction for Pi*e).
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KEYWORD
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AUTHOR
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EXTENSIONS
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Checked by Neven Juric (neven.juric(AT)apis-it.hr), Feb 04 2008
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STATUS
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approved
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