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!)
A146306 a(n) = numerator of (n-6)/(2n) 4
-5, -1, -1, -1, -1, 0, 1, 1, 1, 1, 5, 1, 7, 2, 3, 5, 11, 1, 13, 7, 5, 4, 17, 3, 19, 5, 7, 11, 23, 2, 25, 13, 9, 7, 29, 5, 31, 8, 11, 17, 35, 3, 37, 19, 13, 10, 41, 7, 43, 11, 15, 23, 47, 4, 49, 25, 17, 13, 53, 9, 55, 14, 19, 29, 59, 5, 61, 31, 21, 16, 65, 11, 67, 17, 23, 35, 71, 6, 73, 37 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For denominators see A146307.

General formula (*Artur Jasinski*):

2 Cos[2*Pi/n] = Hypergeometric2F1[(n-6)/(2n),(n+6)/(2n),1/2,3/4] =

Hypergeometric2F1[a(n)/A146307(n),a(n+12)/A146307(n),1/2,3/4].

2 Cos[2*Pi/n] is root of polynomial of degree = EulerPhi[n]/2 = A000010(n)/2 = A023022(n).

Records in this sequence are congruent to 1 or 5 mod 6 (see A007310).

First occurrence n in this sequence see A146308.

LINKS

Table of n, a(n) for n=1..80.

FORMULA

a(n+5)=A051724(n)

MATHEMATICA

Table[Numerator[(n - 6)/(2 n)], {n, 1, 100}] (*Artur Jasinski*)

CROSSREFS

A007310, A051724, A146307, A146308

Sequence in context: A162298 A196755 A199510 * A336697 A326073 A257098

Adjacent sequences:  A146303 A146304 A146305 * A146307 A146308 A146309

KEYWORD

sign

AUTHOR

Artur Jasinski, Oct 29 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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 24 06:56 EDT 2021. Contains 346273 sequences. (Running on oeis4.)