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 A250182 #16 May 21 2018 03:24:55 %S A250182 4,5,7,13,25,33,41,63,74,80,88,94,96,104,116,144,149,151,154,165,167, %T A250182 174,183,191,197,208,231,241,262,268,270,290,318,319,361,368,376,390, %U A250182 394,412,431,434,442,464,489,492,521,529,556,568,574,575,585,589,613,629,639,654,666,667,672,683,684 %N A250182 Numbers n such that Phi_28(n) is prime, where Phi is the cyclotomic polynomial. %H A250182 G. C. Greubel, <a href="/A250182/b250182.txt">Table of n, a(n) for n = 1..10000</a> %t A250182 Select[Range[700], PrimeQ[Cyclotomic[28, #]] &] (* _Vincenzo Librandi_, Jan 17 2015 *) %o A250182 (PARI) isok(n) = isprime(polcyclo(28, n)); \\ _Michel Marcus_, Jan 17 2015 %Y A250182 Cf. A246392. %K A250182 nonn %O A250182 1,1 %A A250182 _R. J. Mathar_, Jan 09 2015