cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A019970 Decimal expansion of tangent of 72 degrees.

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane

Keywords

Comments

Also the decimal expansion of cotangent of 18 degrees. - Mohammad K. Azarian, Jun 30 2013
A quartic integer. - Charles R Greathouse IV, Aug 27 2017
Length of the second longest diagonal in a regular 10-gon with unit side. - Mohammed Yaseen, Nov 12 2020

Examples

			tan(2*Pi/5) = 3.077683537175253402570290576036909824006702143537792427...

Links

Crossrefs

Cf. A019881 (sine of 72 degrees).
Cf. A019904, A019934, A019964.

Programs

  • Magma
    SetDefaultRealField(RealField(100)); Sqrt(5+2*Sqrt(5)); // G. C. Greubel, Nov 21 2018
  • Mathematica
    RealDigits[Tan[72 Degree],10,120][[1]] (* Harvey P. Dale, Apr 30 2012 *)
RealDigits[Sqrt[5 + 2*Sqrt[5]], 10, 100][[1]] (* G. C. Greubel, Nov 21 2018 *)
  • PARI
    tan(2*Pi/5) \\ Charles R Greathouse IV, Aug 27 2017
  • Sage
    numerical_approx(tan(2*pi/5), digits=100) # G. C. Greubel, Nov 21 2018

Formula

Equals sqrt(5 + 2*sqrt(5)). - R. J. Mathar, Jun 18 2006
Equals tan(66 degrees) + tan(36 degrees) + tan(6 degrees). - Amiram Eldar, Apr 07 2022
Largest positive of the 4 real-valued roots of x^4-10*x^2+5=0. - R. J. Mathar, Aug 31 2025

A343057 Decimal expansion of tan(Pi/32).

Original entry on oeis.org

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

Views

Author

Seiichi Manyama, Apr 04 2021

Keywords

Examples

			0.098491403357164253077197...

Links

Crossrefs

Cf. A343055 (sin(Pi/32)), A343056 (cos(Pi/32)).
tan(Pi/m): A002194 (m=3), A019934 (m=5), A020760 (m=6), A343058 (m=7), A188582 (m=8), A019918 (m=9), A019916 (m=10), A019913 (m=12), A343059 (m=14), A019910 (m=15), A343060 (m=16), A343061 (m=17), A019908 (m=18), A019907 (m=20), A343062 (m=24), A019904 (m=30), A343057 (m=32), A019903 (m=36).

Programs

  • Magma
    R:= RealField(125); Tan(Pi(R)/32); // G. C. Greubel, Sep 30 2022
  • Mathematica
    RealDigits[Tan[Pi/32], 10, 120, -1][[1]] (* Amiram Eldar, Apr 27 2021 *)
  • PARI
    tan(Pi/32)
  • PARI
    sqrt((2-sqrt(2+sqrt(2+sqrt(2))))/(2+sqrt(2+sqrt(2+sqrt(2)))))
  • SageMath
    numerical_approx(tan(pi/32), digits=125) # G. C. Greubel, Sep 30 2022

Formula

Equals sqrt( (2-sqrt(2+sqrt(2+sqrt(2))))/(2+sqrt(2+sqrt(2+sqrt(2)))) ).
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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