login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A019946 Decimal expansion of tangent of 48 degrees. 1
1, 1, 1, 0, 6, 1, 2, 5, 1, 4, 8, 2, 9, 1, 9, 2, 8, 7, 0, 1, 4, 3, 4, 8, 1, 9, 6, 4, 1, 6, 5, 1, 3, 5, 5, 3, 2, 5, 7, 6, 9, 5, 9, 5, 1, 0, 3, 9, 0, 8, 5, 9, 0, 4, 8, 1, 8, 4, 4, 0, 2, 2, 2, 0, 2, 8, 9, 9, 6, 5, 5, 3, 5, 8, 7, 3, 7, 3, 1, 3, 6, 5, 4, 5, 8, 5, 0, 6, 1, 6, 9, 2, 1, 5, 8, 7, 8, 6, 8 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Also the decimal expansion of cotangent of 42 degrees. - Ivan Panchenko, Sep 01 2014

LINKS

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

Wikipedia, Exact trigonometric constants

FORMULA

Equals cot(7*Pi/30) = sqrt(23 - 10*sqrt(5) + 2*sqrt(3*(85 -38*sqrt(5)))). - G. C. Greubel, Nov 24 2018

Let r(n) = (n - 1)/(n + 1) if n mod 4 = 1, (n + 1)/(n - 1) otherwise; then this constant equals with Product_{n>=0} r(30*n+15) = (8/7) * (22/23) * (38/37) * (52/53) ... - Dimitris Valianatos, Sep 14 2019

EXAMPLE

1.11061251482919287014348196416513553257695951039085904818440222...

MATHEMATICA

RealDigits[Tan[48 Degree], 10, 120][[1]] (* Harvey P. Dale, Nov 26 2011 *)

RealDigits[Tan[4*Pi/15], 10, 100][[1]] (* G. C. Greubel, Nov 24 2018 *)

PROG

(PARI) default(realprecision, 100); tan(4*Pi/15) \\ G. C. Greubel, Nov 24 2018

(MAGMA) SetDefaultRealField(RealField(100)); R:= RealField(); Tan(4*Pi(R)/15); // G. C. Greubel, Nov 24 2018

(Sage) numerical_approx(tan(4*pi/15), digits=100) # G. C. Greubel, Nov 24 2018

CROSSREFS

Cf. A019857 (sine of 48 degrees).

Sequence in context: A083463 A187110 A013672 * A090551 A220782 A274617

Adjacent sequences:  A019943 A019944 A019945 * A019947 A019948 A019949

KEYWORD

nonn,cons

AUTHOR

N. J. A. Sloane

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 27 05:37 EST 2021. Contains 341649 sequences. (Running on oeis4.)