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Values of totient function applied to squarefree numbers; or numbers of form Product (p_i-1) where p_i are distinct primes.
4

%I #12 Feb 25 2019 10:44:39

%S 1,2,4,6,8,10,12,16,18,20,22,24,28,30,32,36,40,42,44,46,48,52,56,58,

%T 60,64,66,70,72,78,80,82,84,88,92,96,100,102,104,106,108,112,116,120,

%U 126,128,130,132,136,138,140,144,148,150,156,160,162,164,166,168,172,176

%N Values of totient function applied to squarefree numbers; or numbers of form Product (p_i-1) where p_i are distinct primes.

%H Max Alekseyev, <a href="http://home.gwu.edu/~maxal/gpscripts/">PARI scripts for various problems</a>

%F Numbers n such that n = phi(k) and |mu(k)| = 1.

%e 8,120,48 are here as totient functions of squarefree numbers 15, 143, 210. 54 and 110, 294, 342 are missing since there are no squarefree k such that phi(k) = 54, 110, etc.

%o (PARI) isok(n) = {my(v = invphi(n)); (#v) && (#select(x->issquarefree(x), v));} \\ _Michel Marcus_, Feb 25 2019

%Y Terms of A049200 after ordering and omitting multiple occurrences.

%Y Cf. A000010, A005117, A013929, A002174, A002202, A049200.

%K nonn

%O 1,2

%A _Labos Elemer_