%I #23 Aug 21 2023 10:23:49
%S 9,7,8,1,4,7,6,0,0,7,3,3,8,0,5,6,3,7,9,2,8,5,6,6,7,4,7,8,6,9,5,9,9,5,
%T 3,2,4,5,9,7,3,7,8,0,8,8,6,2,6,7,7,1,0,7,8,8,5,1,7,7,6,6,3,6,4,0,5,9,
%U 6,8,3,3,1,2,0,0,9,5,1,2,1,9,9,9,7,5,8,5,2,5,4,5,4,7,8,5,6,3,6
%N Decimal expansion of sine of 78 degrees.
%C Equals sin(13*Pi/30). - _Wesley Ivan Hurt_, Aug 31 2014
%C A quartic number with denominator 2 and minimal polynomial 16x^4 + 8x^3 - 16x^2 - 8x + 1. - _Charles R Greathouse IV_, Aug 27 2017
%H Ivan Panchenko, <a href="/A019887/b019887.txt">Table of n, a(n) for n = 0..1000</a>
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Exact_trigonometric_constants">Exact trigonometric constants</a>
%H <a href="/index/Al#algebraic_04">Index entries for algebraic numbers, degree 4</a>
%F Equals cos(Pi/15) = [sqrt(5)-1]*[1+sqrt(3)*sqrt{5+2*sqrt(5)}]/8 = [A002163-1]*[1+A002194*A019970]/8. - _R. J. Mathar_, Jun 18 2006
%F Equals 2*A019848*A019860. - _R. J. Mathar_, Jan 17 2021
%e 0.9781476007338056379285667478695995324597378088626771078851...
%p Digits:=100: evalf(sin(13*Pi/30)); # _Wesley Ivan Hurt_, Aug 31 2014
%t First@RealDigits[Sin[78 Degree], 10, 120] (* _Michael De Vlieger_, Aug 31 2014 *)
%o (PARI) cos(Pi/15) \\ _Charles R Greathouse IV_, Aug 27 2017
%K nonn,cons
%O 0,1
%A _N. J. A. Sloane_.