A019938 Decimal expansion of tangent of 40 degrees.

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

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• cons
• changed

Comments

Also the decimal expansion of cotangent of 50 degrees. - Ivan Panchenko, Aug 01 2014

Examples

			0.839099631177280011763127298123181364687434283012346533244102...
		

Links

• Ivan Panchenko, Table of n, a(n) for n = 0..1000
• Index entries for algebraic numbers, degree 6.

Crossrefs

Cf. A019849 (sine of 40 degrees).

Programs

Magma

SetDefaultRealField(RealField(100)); R:= RealField(); Tan(2*Pi(R)/9); // G. C. Greubel, Nov 25 2018

Mathematica

RealDigits[Tan[2*Pi/9], 10, 100][[1]] (* G. C. Greubel, Nov 25 2018 *)
RealDigits[Tan[40 Degree],10,120][[1]] (* Harvey P. Dale, Apr 06 2022 *)

PARI

default(realprecision, 100); tan(2*Pi/9) \\ G. C. Greubel, Nov 25 2018

PARI

polrootsreal(x^6-33*x^4+27*x^2-3)[5] \\ Charles R Greathouse IV, Feb 05 2025

Sage

numerical_approx(tan(2*pi/9), digits=100) # G. C. Greubel, Nov 25 2018

Formula

One of the 6 real-valued roots of x^6-33*x^4+27*x^2-3=0. - R. J. Mathar, Aug 31 2025

Equals A019849/A019859. - R. J. Mathar, Aug 31 2025