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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A306371 Number of primitive roots of prime A103521(n). 0
1, 2, 4, 6, 8, 12, 16, 20, 24, 32, 36, 40, 48, 64, 72, 80, 96, 120, 144, 160, 176, 200, 216, 240, 288, 320, 336, 384, 432, 448, 480, 576, 720, 768, 880, 960, 1056, 1200, 1280, 1344, 1440, 1664, 1680, 1728, 1920, 2112, 2208, 2304, 2400, 2592, 2784, 2880, 3072, 3456, 3840, 4224, 4320 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers k in A008330 such that no numbers <= k occur later than k in A008330.

Different from A036912 since a(19) = 144 and A036912(19) = 128.

LINKS

Table of n, a(n) for n=1..57.

FORMULA

a(n) = phi(A103521(n)-1).

PROG

(PARI) b(n) = if(n==1, 2, floor(exp(Euler)*n*log(log(n^2))+2.5*n/log(log(n^2))));

f(p) = my(i=0); forprime(q=p+1, b(eulerphi(p-1))+1, i+=(eulerphi(q-1)<=eulerphi(p-1))); i;

forprime(p=2, 2e4, if(f(p)==0, print1(eulerphi(p-1), ", ")))

CROSSREFS

Cf. A103521.

Cf. also A103203, A121519.

Sequence in context: A182568 A064522 A036912 * A097921 A185976 A117146

Adjacent sequences:  A306368 A306369 A306370 * A306372 A306373 A306374

KEYWORD

nonn

AUTHOR

Jianing Song, Feb 11 2019

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 October 18 00:55 EDT 2019. Contains 328135 sequences. (Running on oeis4.)