A059109 Numbers m such that m*phi(m)-1 is prime, where phi is the Euler function (A000010).

3, 4, 5, 6, 7, 8, 9, 11, 12, 14, 16, 17, 18, 21, 24, 25, 26, 29, 30, 31, 33, 35, 36, 38, 42, 47, 54, 61, 63, 65, 66, 67, 71, 74, 75, 78, 81, 87, 91, 97, 99, 101, 105, 117, 119, 121, 123, 127, 128, 131, 132, 135, 139, 140, 143, 144, 147, 149, 154, 156, 158, 162, 172

Offset: 1

Author

Jud McCranie, Jan 03 2001

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A046078.

Programs

Magma

[n: n in [1..200] | IsPrime(n*EulerPhi(n)-1)]; // Vincenzo Librandi, Jul 31 2018

Mathematica

Select[Range[200],PrimeQ[# EulerPhi[#]-1]&] (* Harvey P. Dale, Aug 23 2012 *)

PARI

is(n)=isprime(n*eulerphi(n)-1) \\ Charles R Greathouse IV, Feb 21 2013