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A039767 Numbers k such that gcd(phi(k), k-1) = number of prime factors of (k-1). 0

%I #7 Oct 26 2019 02:08:12

%S 4,6,8,10,12,14,15,18,20,24,26,27,30,32,35,38,39,42,44,48,50,51,54,55,

%T 60,62,63,68,72,74,75,80,81,82,84,87,90,95,98,99,102,104,108,110,114,

%U 119,122,123,126,128,132,135,138,140,143,147,150,152,158,159,164,168

%N Numbers k such that gcd(phi(k), k-1) = number of prime factors of (k-1).

%e phi(15)=8, gcd(8,14)=2, 14=2*7, 2 prime factors.

%Y Cf. A000010, A001221.

%K nonn,easy

%O 1,1

%A _Olivier GĂ©rard_

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Last modified March 29 08:59 EDT 2024. Contains 371268 sequences. (Running on oeis4.)