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 A261535 #20 Nov 17 2015 09:21:59
%S A261535 2,17,1297,331777,1503561738404723998944447273369600000001
%N A261535 Primes of the form Phi(8,n!), where Phi is the cyclotomic polynomial.
%C A261535 a(6) is 730 digits.
%H A261535 OEIS Wiki, <a href="https://oeis.org/wiki/Cyclotomic Polynomials at x=n, n! and sigma(n)">Cyclotomic Polynomials at x=n, n! and sigma(n)</a>
%t A261535 Select[Table[Cyclotomic[8, n!], {n, 0, 200}], PrimeQ]
%o A261535 (PARI) for(n=1, 500, if(isprime(k=polcyclo(8, n!)), print1(k", "))) \\ _Altug Alkan_, Nov 16 2015
%Y A261535 Cf. A123865, A200906, A259264, A259265, A260478.
%K A261535 nonn
%O A261535 1,1
%A A261535 _Robert Price_, Aug 28 2015