A207574 Numbers k such that phi(k)+2 divides k+2.

1, 6, 10, 14, 22, 26, 34, 38, 46, 58, 62, 74, 82, 86, 94, 106, 118, 122, 134, 142, 146, 158, 166, 178, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 390, 394, 398, 422, 446, 454, 458, 466, 478

Offset: 1

Author

José María Grau Ribas, Feb 19 2012

Keywords

• nonn
• easy

Comments

Consists of the even semiprimes (other than 4) together with A207575. - Charles R Greathouse IV, Jul 15 2013

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A207575, A202855, A203966.

Programs

Mathematica

Select[Range[1000],Divisible[#+2,EulerPhi[#]+2]&]

PARI

isA207574(n)={
        if( (n+2) % (eulerphi(n)+2) ==0,1,0) ;
}
{
for(n=1,200,
        if (isA207574(n) , print(n)) ;
) ;
} /* R. J. Mathar, Feb 23 2012 */