A226105 - OEIS

%I #24 Nov 05 2023 10:21:32

%S 1,195,5187,1141967133868035,3658018932844533311864835

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

%C Terms having (k+3)/(phi(k)+3) = 2 are shared with A350777. - _Max Alekseyev_, Oct 26 2023

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

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

%Y Set difference of A226104 and 6 * A000040.

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

%K nonn,hard,more

%O 1,2

%A _José María Grau Ribas_, May 26 2013

%E Edited and a(4)-a(5) added by _Max Alekseyev_, Nov 5 2023