A019976 - OEIS

%I #25 Jun 28 2026 15:47:50

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

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

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

%N Decimal expansion of tangent of 78 degrees.

%C Also the decimal expansion of cotangent of 12 degrees. - _Ivan Panchenko_, Sep 01 2014

%C An algebraic integer of degree 8. - _Charles R Greathouse IV_, Nov 05 2017

%H Ivan Panchenko, <a href="/A019976/b019976.txt">Table of n, a(n) for n = 1..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 Equals A019887 / A019821 = A019833/(1-A019875) . - _R. J. Mathar_, Sep 06 2025

%F Minimal polynomial x^8 -28*x^6 +134*x^4 -92*x^2 +1. - _R. J. Mathar_, Jun 03 2026

%e tan(13*Pi/30) = 4.704630109478454233586234537402900275699260747802...

%t First[RealDigits[Tan[78 Degree], 10, 100]] (* _Paolo Xausa_, Nov 16 2025 *)

%o (PARI) 1/tan(Pi/15) \\ _Charles R Greathouse IV_, Nov 05 2017

%K nonn,cons,easy

%O 1,1

%A _N. J. A. Sloane_