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%I #14 Feb 18 2021 02:38:52
%S 1,2,4,6,8,24,36,48,80,192,1440,3960,5184,5478,6480,16080,20336,29628,
%T 40073,40083,43056,44980,85800,200320,241920,252378,258048,287040,
%U 697248,1805672,3669120,3713787,3927600,4321143,4448880,6928128
%N Numbers k such that phi(prime(k) + 1) == 0 (mod k).
%t Do[ If[ Mod[ EulerPhi[ Prime[n] + 1], n] == 0, Print[n]], {n, 1, 10^7} ]
%o (PARI) isok(k) = (eulerphi(prime(k)+1) % k) == 0; \\ _Michel Marcus_, Feb 17 2021
%Y Cf. A008331.
%K nonn
%O 1,2
%A _Benoit Cloitre_, Feb 05 2002
%E Edited and extended by _Robert G. Wilson v_, Feb 07 2002
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