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 A250195 #12 May 21 2018 03:22:51
%S A250195 1,2,5,62,67,104,123,138,151,186,194,233,236,261,269,306,359,416,425,
%T A250195 439,557,613,695,705,742,748,821,832,884,885,892,902,936,937,1125,
%U A250195 1165,1176,1248,1265,1320,1337,1386,1544,1594,1675,1707,1712,1714,1722,1725,1798,1840,1844
%N A250195 Numbers n such that Phi(49,n) is prime, where Phi is the cyclotomic polynomial.
%H A250195 G. C. Greubel, <a href="/A250195/b250195.txt">Table of n, a(n) for n = 1..10000</a>
%t A250195 Select[Range[1900], PrimeQ[Cyclotomic[49, #]] &] (* _Vincenzo Librandi_, Jan 17 2015 *)
%o A250195 (PARI) {is(n)=isprime(polcyclo(49,n))};
%o A250195 for(n=1,1000, if(is(n), print1(n, ", "))) \\ _G. C. Greubel_, May 20 2018
%Y A250195 Cf. A246392.
%K A250195 nonn
%O A250195 1,2
%A A250195 _R. J. Mathar_, Jan 12 2015