A226105 - OEIS

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

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OFFSET

1,2

COMMENTS

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

LINKS

MATHEMATICA

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

PROG

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

CROSSREFS

Set difference of A226104 and 6 * A000040.

KEYWORD

nonn,hard,more

AUTHOR

EXTENSIONS

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

STATUS

approved