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A250195 Numbers n such that Phi(49,n) is prime, where Phi is the cyclotomic polynomial. 2

%I

%S 1,2,5,62,67,104,123,138,151,186,194,233,236,261,269,306,359,416,425,

%T 439,557,613,695,705,742,748,821,832,884,885,892,902,936,937,1125,

%U 1165,1176,1248,1265,1320,1337,1386,1544,1594,1675,1707,1712,1714,1722,1725,1798,1840,1844

%N Numbers n such that Phi(49,n) is prime, where Phi is the cyclotomic polynomial.

%H G. C. Greubel, <a href="/A250195/b250195.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[1900], PrimeQ[Cyclotomic[49, #]] &] (* _Vincenzo Librandi_, Jan 17 2015 *)

%o (PARI) {is(n)=isprime(polcyclo(49,n))};

%o for(n=1,1000, if(is(n), print1(n, ", "))) \\ _G. C. Greubel_, May 20 2018

%Y Cf. A246392.

%K nonn

%O 1,2

%A _R. J. Mathar_, Jan 12 2015

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Last modified October 21 17:37 EDT 2021. Contains 348155 sequences. (Running on oeis4.)