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 A250196 #12 May 21 2018 03:22:58
%S A250196 6,7,17,42,56,62,106,108,112,141,161,163,173,210,212,231,296,306,342,
%T A250196 360,382,395,400,416,418,431,435,457,458,492,517,530,531,540,551,618,
%U A250196 637,672,697,713,722,732,790,791,810,850,852,876,898,902,926,928,937,938,970,1010,1091,1118,1123,1150,1157,1165
%N A250196 Numbers n such that Phi(50,n) is prime, where Phi is the cyclotomic polynomial.
%H A250196 G. C. Greubel, <a href="/A250196/b250196.txt">Table of n, a(n) for n = 1..10000</a>
%t A250196 Select[Range[1200], PrimeQ[Cyclotomic[50, #]] &] (* _Vincenzo Librandi_, Jan 16 2015 *)
%o A250196 (PARI) {is(n)=isprime(polcyclo(50,n))};
%o A250196 for(n=1,1000, if(is(n), print1(n, ", "))) \\ _G. C. Greubel_, May 20 2018
%Y A250196 Cf. A246392.
%K A250196 nonn
%O A250196 1,1
%A A250196 _R. J. Mathar_, Jan 12 2015