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 A205796 #10 Jun 13 2017 13:48:04
%S A205796 1,9,33,69,427,1009,2667
%N A205796 Numbers n such that 4*17^n - 1 is prime.
%t A205796 Table[If[PrimeQ[4*17^n-1],Print[n];n],{n,1,20000}]
%o A205796 (PARI) is(n)=ispseudoprime(4*17^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y A205796 Cf. A180431 (numbers n such that 4*17^n + 1 is prime).
%Y A205796 Cf. A205521 (numbers n such that 4*11^n - 1 is prime).
%Y A205796 Cf. A046865 (numbers n such that 4*5^n - 1 is prime).
%Y A205796 Cf. A005540 (numbers n such that 4*3^n - 1 is prime).
%K A205796 nonn
%O A205796 1,2
%A A205796 _José María Grau Ribas_, Jan 31 2012