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 A261487 #6 Aug 28 2015 17:31:39
%S A261487 7,127,55987,
%T A261487 58301791288260114251803544692993535976160443849938371660801
%N A261487 Primes of the form Phi(7,n!), where Phi is the cyclotomic polynomial.
%H A261487 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 A261487 Select[Table[Cyclotomic[7, n!], {n, 0, 200}], PrimeQ]
%Y A261487 Cf. A053716, A200906, A258357, A259264, A259265.
%K A261487 nonn
%O A261487 1,1
%A A261487 _Robert Price_, Aug 20 2015