A219028 Number of non-primitive roots for prime(n), less than prime(n).

0, 1, 2, 4, 6, 8, 8, 12, 12, 16, 22, 24, 24, 30, 24, 28, 30, 44, 46, 46, 48, 54, 42, 48, 64, 60, 70, 54, 72, 64, 90, 82, 72, 94, 76, 110, 108, 108, 84, 88, 90, 132, 118, 128, 112, 138, 162, 150, 114, 156, 120, 142, 176, 150, 128, 132, 136, 198, 188, 184, 190

Offset

1,3

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

a(n) = p - 1 - phi(phi(p)), where p is the n-th prime.

a(n) = p - 1 - A008330(n) = p - 1 - A010554(p), where p is the n-th prime. - V. Raman, Nov 22 2012

Mathematica

Table[c=Prime[n]; c-1-EulerPhi[EulerPhi[c]], {n, 70}] (* Harvey P. Dale, Feb 12 2013 *)

Prog

(PARI) forprime(i=2, 600, p=0; for(q=1, i-1, if(znorder(Mod(q, i))!=eulerphi(i), p++)); print1(p", "))

Crossrefs

Cf. A008330 (number of primitive roots for the n-th prime, less than n-th prime).

Cf. A046144 (number of primitive roots for n, less than n).

Cf. A010554 (value of phi(phi(n))).

Sequence in context: A060659 A244363 A063199 * A333557 A062355 A366602

Adjacent sequences: A219025 A219026 A219027 * A219029 A219030 A219031

Keyword

nonn

Author

V. Raman, Nov 10 2012

Status

approved