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A019946
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Decimal expansion of tangent of 48 degrees.
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1
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1, 1, 1, 0, 6, 1, 2, 5, 1, 4, 8, 2, 9, 1, 9, 2, 8, 7, 0, 1, 4, 3, 4, 8, 1, 9, 6, 4, 1, 6, 5, 1, 3, 5, 5, 3, 2, 5, 7, 6, 9, 5, 9, 5, 1, 0, 3, 9, 0, 8, 5, 9, 0, 4, 8, 1, 8, 4, 4, 0, 2, 2, 2, 0, 2, 8, 9, 9, 6, 5, 5, 3, 5, 8, 7, 3, 7, 3, 1, 3, 6, 5, 4, 5, 8, 5, 0, 6, 1, 6, 9, 2, 1, 5, 8, 7, 8, 6, 8
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OFFSET
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1,5
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COMMENTS
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Also the decimal expansion of cotangent of 42 degrees. - Ivan Panchenko, Sep 01 2014
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LINKS
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Ivan Panchenko, Table of n, a(n) for n = 1..1000
Wikipedia, Exact trigonometric constants
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FORMULA
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Equals cot(7*Pi/30) = sqrt(23 - 10*sqrt(5) + 2*sqrt(3*(85 -38*sqrt(5)))). - G. C. Greubel, Nov 24 2018
Let r(n) = (n - 1)/(n + 1) if n mod 4 = 1, (n + 1)/(n - 1) otherwise; then this constant equals with Product_{n>=0} r(30*n+15) = (8/7) * (22/23) * (38/37) * (52/53) ... - Dimitris Valianatos, Sep 14 2019
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EXAMPLE
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1.11061251482919287014348196416513553257695951039085904818440222...
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MATHEMATICA
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RealDigits[Tan[48 Degree], 10, 120][[1]] (* Harvey P. Dale, Nov 26 2011 *)
RealDigits[Tan[4*Pi/15], 10, 100][[1]] (* G. C. Greubel, Nov 24 2018 *)
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PROG
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(PARI) default(realprecision, 100); tan(4*Pi/15) \\ G. C. Greubel, Nov 24 2018
(MAGMA) SetDefaultRealField(RealField(100)); R:= RealField(); Tan(4*Pi(R)/15); // G. C. Greubel, Nov 24 2018
(Sage) numerical_approx(tan(4*pi/15), digits=100) # G. C. Greubel, Nov 24 2018
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CROSSREFS
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Cf. A019857 (sine of 48 degrees).
Sequence in context: A083463 A187110 A013672 * A090551 A220782 A274617
Adjacent sequences: A019943 A019944 A019945 * A019947 A019948 A019949
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KEYWORD
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nonn,cons
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AUTHOR
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N. J. A. Sloane
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STATUS
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approved
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