login
This site is supported by donations to The OEIS Foundation.

 

Logo

The OEIS is looking to hire part-time people to help edit core sequences, upload scanned documents, process citations, fix broken links, etc. - Neil Sloane, njasloane@gmail.com

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A144981 Decimal expansion of cos(Pi/8) = cos(22.5 degrees). 8
9, 2, 3, 8, 7, 9, 5, 3, 2, 5, 1, 1, 2, 8, 6, 7, 5, 6, 1, 2, 8, 1, 8, 3, 1, 8, 9, 3, 9, 6, 7, 8, 8, 2, 8, 6, 8, 2, 2, 4, 1, 6, 6, 2, 5, 8, 6, 3, 6, 4, 2, 4, 8, 6, 1, 1, 5, 0, 9, 7, 7, 3, 1, 2, 8, 0, 5, 3, 5, 0, 0, 7, 5, 0, 1, 1, 0, 2, 3, 5, 8, 7, 1, 4, 8, 3, 9, 9, 3, 4, 8, 5, 0, 3, 4, 4, 5, 9, 6, 0, 9, 7, 9, 6, 3 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Also the real part of i^(1/4). - Stanislav Sykora, Apr 25 2012

LINKS

Table of n, a(n) for n=0..104.

Wikipedia, Exact trigonometric constants.

FORMULA

(2+2^(1/2))^(1/2)/2 = sqrt(3.41421....)/2 = 1.8477759.../2 .

Equals 2F1(11/16,5/16;1/2;3/4) / 2. - R. J. Mathar, Oct 27 2008

EXAMPLE

Equals 0.923879532511286756128183189396788286822416625863642486115097...

MAPLE

evalf(sqrt(2+sqrt(2))/2) ;

MATHEMATICA

RealDigits[ Sqrt[2 + Sqrt[2]]/2, 10, 111][[1]] (* Or *) RealDigits[ Cos[Pi/8], 10, 111][[1]] (* Robert G. Wilson v *)

PROG

(PARI) cos(Pi/8) \\ Michel Marcus, Dec 15 2015

CROSSREFS

Cf. A019863: cos(Pi/5); A010527: cos(Pi/6); A073052: cos(Pi/7); A019879: cos(Pi/9).

Sequence in context: A011344 A257959 A137197 * A215267 A248322 A248321

Adjacent sequences:  A144978 A144979 A144980 * A144982 A144983 A144984

KEYWORD

cons,easy,nonn

AUTHOR

R. J. Mathar, Sep 28 2008

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified May 27 16:49 EDT 2017. Contains 287207 sequences.