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%I #33 Aug 21 2023 11:41:59
%S 1,5,6,4,3,4,4,6,5,0,4,0,2,3,0,8,6,9,0,1,0,1,0,5,3,1,9,4,6,7,1,6,6,8,
%T 9,2,3,1,3,8,9,9,8,9,2,0,8,5,6,6,0,7,9,0,0,8,4,6,4,1,3,4,6,0,5,7,7,5,
%U 8,7,9,3,3,0,5,6,2,3,5,7,9,3,3,6,6,9,5,8,7,2,6,7,6,8,4,8,6,8,8
%N Decimal expansion of sine of 9 degrees.
%C Also the imaginary part of i^(1/10). - _Stanislav Sykora_, Apr 25 2012
%C An algebraic number of degree 8 and denominator 2. - _Charles R Greathouse IV_, Aug 27 2017
%H Ivan Panchenko, <a href="/A019818/b019818.txt">Table of n, a(n) for n = 0..1000</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Exact_trigonometric_constants">Exact trigonometric constants</a>
%H <a href="/index/Al#algebraic_08">Index entries for algebraic numbers, degree 8</a>
%F sqrt(8-2*sqrt(10+2*sqrt(5)))/4 = sqrt((1/2)*(1 - sqrt((1/8)*(5 + sqrt(5))))). - Herman Jamke (hermanjamke(AT)fastmail.fm), Nov 13 2006
%F Equals A019815*A019896 + A019812*A019893. - _R. J. Mathar_, Jan 27 2021
%e 0.1564344650402308690101053194671668923138...
%t RealDigits[Sin[9 Degree],10,120][[1]] (* _Harvey P. Dale_, Sep 15 2014 *)
%o (PARI) sin(Pi/20) \\ _Charles R Greathouse IV_, Aug 27 2017
%Y Cf. A019812, A019815, A019893, A019896.
%K nonn,cons
%O 0,2
%A _N. J. A. Sloane_
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