A019968 Decimal expansion of tangent of 70 degrees.

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

Offset

1,1

Comments

Also the decimal expansion of cotangent of 20 degrees. - Ivan Panchenko, Sep 01 2014

An algebraic number of degree 6 and denominator 3. - Charles R Greathouse IV, Aug 27 2017

Links

Ivan Panchenko, Table of n, a(n) for n = 1..1000

Index entries for algebraic numbers, degree 6

Formula

Equals A019879/A019829. - R. J. Mathar, Aug 29 2025

Largest positive of the 6 real-values roots of 3*x^6 -27*x^4 +33*x^2 -1 =0. (Others: A019948, A019908). - R. J. Mathar, Aug 29 2025

Example

2.7474774194546222787616640264976727177518725991708258215...

Mathematica

RealDigits[Tan[7*Pi/18], 10, 100][[1]] (* G. C. Greubel, Nov 21 2018 *)

Prog

(PARI) tan(7*Pi/18) \\ Charles R Greathouse IV, Aug 27 2017
(Magma) SetDefaultRealField(RealField(100)); R:= RealField(); Tan(7*Pi(R)/18); // G. C. Greubel, Nov 21 2018
(SageMath) numerical_approx(tan(7*pi/18), digits=100) # G. C. Greubel, Nov 21 2018

Crossrefs

Cf. A019879 (sine of 70 degrees).

Sequence in context: A175641 A286984 A021368 * A257434 A011050 A198935

Adjacent sequences: A019965 A019966 A019967 * A019969 A019970 A019971

Keyword

nonn,cons

Author

N. J. A. Sloane

Status

approved