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 A291994 #9 Nov 11 2019 13:48:24
%S A291994 31,37,43,1297,46441,51828151,55987,1950271,2527867231,1678321,
%T A291994 3655688315536801,189491931189200021056951,1822428931,
%U A291994 412482688627178079807598675848631,4760317816590150361,534577564460822791430647883899825591,7369130657357778596659
%N A291994 Primes of the form Phi(k, -6), where Phi is the cyclotomic polynomial.
%H A291994 Robert Price, <a href="/A291994/b291994.txt">Table of n, a(n) for n = 1..26</a>
%H A291994 Yves Gallot, <a href="http://yves.gallot.pagesperso-orange.fr/papers/cyclotomic.html">Cyclotomic polynomials and prime numbers</a>
%H A291994 <a href="/index/Cy#CyclotomicPolynomialsValuesAtX">Index entries for cyclotomic polynomials,values at X</a>
%t A291994 Select[Table[Cyclotomic[k,-6], {k, 0, 100}], PrimeQ[#] &]
%Y A291994 Cf. A138924.
%K A291994 nonn
%O A291994 1,1
%A A291994 _Robert Price_, Sep 07 2017