A241195 Denominator of phi(prime(n)-1)/(prime(n)-1), where phi is Euler's totient function and prime(n) is the n-th prime.

1, 2, 2, 3, 5, 3, 2, 3, 11, 7, 15, 3, 5, 7, 23, 13, 29, 15, 33, 35, 3, 13, 41, 11, 3, 5, 51, 53, 3, 7, 7, 65, 17, 69, 37, 15, 13, 3, 83, 43, 89, 15, 95, 3, 7, 33, 35, 37, 113, 19, 29, 119, 15, 5, 2, 131, 67, 15, 69, 35, 141, 73, 51, 31, 13, 79, 33, 7, 173, 87, 11

Offset: 1

Author

T. D. Noe, Apr 17 2014

Keywords

• nonn
• frac

Comments

The numerators are in A241194.

Links

• T. D. Noe, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010 (phi), A241194 (numerators).

Cf. A109395, A006093.

Programs

Magma

[Denominator(EulerPhi(NthPrime(n)-1)/(NthPrime(n)-1)): n in [1..80]]; // Vincenzo Librandi, Apr 06 2015

Maple

with(numtheory): A241195:=n->denom(phi(ithprime(n)-1) / (ithprime(n)-1)): seq(A241195(n), n=1..100); # Wesley Ivan Hurt, Apr 06 2015

Mathematica

Denominator[Table[EulerPhi[p - 1]/(p - 1), {p, Prime[Range[100]]}]]

PARI

lista(nn) = forprime(p=2, nn, print1(denominator(eulerphi(p-1)/(p-1)), ", ")); \\ Michel Marcus, Jan 03 2015

Formula

a(n) = A109395(A006093(n)). - Ridouane Oudra, Mar 24 2025