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A066936 Integers k such that prime(k)-1 == 0 (mod phi(k)) where prime(n)=A000040(n) is the n-th prime and phi(n)=A000010(n) is the Euler totient function. 3

%I

%S 1,2,3,4,6,10,11,12,14,18,21,24,30,38,42,46,67,84,87,110,121,136,159,

%T 279,306,378,428,439,516,662,682,726,1046,1110,1199,1410,1687,2160,

%U 2244,2438,2450,2612,2614,2654,3270,3477,3829,7107,7178,8682,9260

%N Integers k such that prime(k)-1 == 0 (mod phi(k)) where prime(n)=A000040(n) is the n-th prime and phi(n)=A000010(n) is the Euler totient function.

%H Harry J. Smith, <a href="/A066936/b066936.txt">Table of n, a(n) for n = 1..94</a>

%t Select[Range[1, 10000], Mod[Prime[ # ]-1, EulerPhi[ # ]]==0&]

%o (PARI) { default(primelimit, 4294965247); n=0; for (m=1, 10^10, if ((prime(m) - 1) % eulerphi(m) == 0, write("b066936.txt", n++, " ", m); if (n==1000, return)) ) } \\ _Harry J. Smith_, Apr 09 2010

%o (MAGMA) [n:n in [1..10000]| IsIntegral((NthPrime(n)-1)/EulerPhi(n))]; // _Marius A. Burtea_, Mar 25 2019

%Y Cf. A000010, A000040.

%K nonn

%O 1,2

%A _Benoit Cloitre_, Jan 24 2002

%E Edited by _Dean Hickerson_, Jan 27 2002

%E Definition corrected by _Harry J. Smith_, Apr 09 2010

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Last modified June 19 08:58 EDT 2021. Contains 345126 sequences. (Running on oeis4.)