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 A211875 #11 Feb 21 2013 15:06:18 %S A211875 2,7,61,73,6481,530713,42521761,47763361,23535794707,282429005041, %T A211875 374857981681,150094634909578633,13490012358249728401, %U A211875 105919308797935444986721,1076050302914923449767311155851656076154481 %N A211875 Primes of the form Phi(phi(k),3), the phi(k)-th Cyclotomic polynomial evaluated at 3, where phi is the Euler totient function. %t A211875 Union[Select[Cyclotomic[EulerPhi[#], x] /. x -> 3 & /@ Range[1000], PrimeQ]] %K A211875 nonn %O A211875 1,1 %A A211875 _Alexander Gruber_, Feb 12 2013