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 A219705 Decimal expansion of cos(log(2)). 2
 7, 6, 9, 2, 3, 8, 9, 0, 1, 3, 6, 3, 9, 7, 2, 1, 2, 6, 5, 7, 8, 3, 2, 9, 9, 9, 3, 6, 6, 1, 2, 7, 0, 7, 0, 1, 4, 4, 0, 8, 9, 5, 9, 9, 4, 9, 1, 1, 9, 6, 3, 8, 5, 3, 1, 6, 9, 8, 7, 1, 5, 0, 7, 4, 2, 9, 0, 8, 1, 3, 4, 6, 8, 0, 7, 3, 4, 0, 7, 8, 9, 0, 5, 9, 7, 8, 9, 7, 4, 2, 4, 2, 6, 0, 1, 6, 8, 0, 7, 2, 7, 1, 2, 9, 5 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS In a letter to Christian Goldbach dated December 9, 1741, Leonhard Euler gave 10/13 as a rational approximation of this number. Also, real part of 2^i. - Bruno Berselli, Dec 31 2012 The imaginary part of 2^i is A220085. - Robert G. Wilson v, Feb 04 2013 REFERENCES W. Michael Kelley, The Humongous Book of Calculus Problems. New York: Alpha Books (Penguin Group) p. 233, Problem 15.22. LINKS Paul J. Nahin, An Imaginary Tale: The Story of sqrt(-1), Princeton, New Jersey: Princeton University Press (1988), 143 - 144. Elizabeth Volz and Hieu D. Nguyen, Euler, Goldbach and exact values of trigonometric functions, 2008 preprint FORMULA cos(log(2)) = (2^i + 2^(-i))/2. EXAMPLE 0.76923890136... MATHEMATICA RealDigits[Cos[Log[2]], 10, 105][[1]] PROG (PARI) cos(log(2)) \\ Charles R Greathouse IV, Nov 25 2012 (Maxima) fpprec:110; ev(bfloat(cos(log(2)))); /* Bruno Berselli, Dec 31 2012 */ CROSSREFS Cf. A002162, A021017, A220085 (imaginary part of 2^i). Sequence in context: A011220 A198605 A021017 * A273066 A257964 A178816 Adjacent sequences:  A219702 A219703 A219704 * A219706 A219707 A219708 KEYWORD nonn,cons AUTHOR Alonso del Arte, Nov 25 2012 EXTENSIONS a(43) ff. corrected by Georg Fischer, Apr 03 2020 STATUS approved

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Last modified June 16 21:55 EDT 2021. Contains 345080 sequences. (Running on oeis4.)