A226104 - OEIS

%I #16 Jan 31 2021 03:06:20

%S 1,30,42,66,78,102,114,138,174,186,195,222,246,258,282,318,354,366,

%T 402,426,438,474,498,534,582,606,618,642,654,678,762,786,822,834,894,

%U 906,942,978,1002,1038,1074,1086,1146,1158,1182,1194,1266,1338,1362,1374,1398

%N Numbers n such that phi(n)+3 divides n+3.

%H Charles R Greathouse IV, <a href="/A226104/b226104.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[2000], IntegerQ[(# + 3)/(EulerPhi[#] + 3)] &]

%o (PARI) is(n)=(n+3)%(eulerphi(n)+3)==0 \\ _Charles R Greathouse IV_, Nov 13 2013

%o (Python)

%o from sympy import totient as phi

%o def ok(n): return (n+3) % (phi(n)+3) == 0

%o print([m for m in range(1, 1400) if ok(m)]) # _Michael S. Branicky_, Jan 30 2021

%Y Cf. A000010 (Euler's totient function).

%Y Cf. A207574 (numbers n such that phi(n)+2 divides n+2).

%Y Cf. A202855 (numbers n such that phi(n)-1 divides n).

%Y Cf. A203966 (numbers n such that phi(n) divides n+1).

%K nonn

%O 1,2

%A _José María Grau Ribas_, May 26 2013