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%I #14 Apr 15 2018 04:03:24
%S 2,6,7,8,9,16,18,20,26,29,31,32,33,40,41,47,57,76,82,87,88,93,101,109,
%T 120,121,125,133,140,144,162,163,175,178,183,186,191,196,215,216,218,
%U 227,233,242,253,266,267,273,276,278,304,312,317,319,328,336,374,380
%N Numbers n such that Phi(30,n) is prime, where Phi is the cyclotomic polynomial.
%H G. C. Greubel, <a href="/A250183/b250183.txt">Table of n, a(n) for n = 1..10000</a>
%t Select[Range[400], PrimeQ[Cyclotomic[30, #]] &] (* _Vincenzo Librandi_, Jan 17 2015 *)
%o (PARI) isok(n) = isprime(polcyclo(30, n)); \\ _Michel Marcus_, Jan 17 2015
%Y Cf. A246392.
%K nonn
%O 1,1
%A _R. J. Mathar_, Jan 12 2015
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