A019982 - OEIS

%I #18 Apr 25 2024 09:21:32

%S 9,5,1,4,3,6,4,4,5,4,2,2,2,5,8,4,9,2,9,6,8,3,9,7,1,4,5,4,9,4,5,6,8,2,

%T 4,6,6,6,4,8,7,6,8,1,4,5,1,5,0,6,5,9,2,2,7,3,1,1,2,6,4,8,9,1,4,6,9,8,

%U 1,0,6,9,9,9,9,7,1,6,7,4,9,4,2,7,3,5,4,2,3,1,2,1,7,3,9,3,7,8,2

%N Decimal expansion of tangent of 84 degrees.

%C Also the decimal expansion of cotangent of 6 degrees. - _Ivan Panchenko_, Sep 01 2014

%H Ivan Panchenko, <a href="/A019982/b019982.txt">Table of n, a(n) for n = 1..1000</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Exact_trigonometric_constants">Exact trigonometric constants</a>.

%F From _Amiram Eldar_, Apr 07 2022: (Start)

%F Equals tan(78 degrees) + tan(72 degrees) + tan(60 degrees).

%F Equals sqrt(23 + 10*sqrt(5) + 2*sqrt(3*(85 + 38*sqrt(5)))).

%F The 4th positive and largest root of x^8 - 92*x^6 + 134*x^4 - 28*x^2 + 1 = 0. (End)

%t RealDigits[Tan[7*Pi/15], 10, 100][[1]] (* _Amiram Eldar_, Apr 07 2022 *)

%Y Cf. A019970, A019976.

%K nonn,cons

%O 1,1

%A _N. J. A. Sloane_