A226105 Numbers k such that phi(k)+3 divides k+3, excluding numbers of the form 6*p for a prime p.

1, 195, 5187, 1141967133868035, 3658018932844533311864835

Offset: 1

Author

José María Grau Ribas, May 26 2013

Keywords

• nonn
• hard
• more

Comments

Terms having (k+3)/(phi(k)+3) = 2 are shared with A350777. - Max Alekseyev, Oct 26 2023

Crossrefs

Set difference of A226104 and 6 * A000040.

Cf. A202855, A203966, A207575, A207667, A350777.

Programs

Mathematica

Select[Range[10000000], !PrimeQ[#/6] && IntegerQ[(# + 3)/(EulerPhi[#] + 3)] &]

PARI

for(n=1,10^8, if( (n+3)%(eulerphi(n)+3)==0 && (n%6 || !isprime(n\6)), print(n)));

Extensions

Edited and a(4)-a(5) added by Max Alekseyev, Nov 05 2023