A306371 Number of primitive roots of prime A103521(n).

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

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 * A333255 A346729 A346311

Adjacent sequences: A306368 A306369 A306370 * A306372 A306373 A306374

Keyword

nonn

Author

Jianing Song, Feb 11 2019

Status

approved