This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A250183 #14 Apr 15 2018 04:03:24 %S A250183 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 A250183 120,121,125,133,140,144,162,163,175,178,183,186,191,196,215,216,218, %U A250183 227,233,242,253,266,267,273,276,278,304,312,317,319,328,336,374,380 %N A250183 Numbers n such that Phi(30,n) is prime, where Phi is the cyclotomic polynomial. %H A250183 G. C. Greubel, <a href="/A250183/b250183.txt">Table of n, a(n) for n = 1..10000</a> %t A250183 Select[Range[400], PrimeQ[Cyclotomic[30, #]] &] (* _Vincenzo Librandi_, Jan 17 2015 *) %o A250183 (PARI) isok(n) = isprime(polcyclo(30, n)); \\ _Michel Marcus_, Jan 17 2015 %Y A250183 Cf. A246392. %K A250183 nonn %O A250183 1,1 %A A250183 _R. J. Mathar_, Jan 12 2015