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 A209120 #21 Jan 01 2019 07:02:09 %S A209120 3,197,3581,6871,183661 %N A209120 Numbers n such that (33^n - 1)/32 is prime. %H A209120 H. Dubner, <a href="http://dx.doi.org/10.1090/S0025-5718-1993-1185243-9">Generalized repunit primes</a>, Math. Comp., 61 (1993), 927-930. %H A209120 H. Lifchitz, <a href="http://www.primenumbers.net/Henri/us/MersFermus.htm">Mersenne and Fermat primes field</a> %H A209120 <a href="/index/Pri#primepop">Index to primes in various ranges</a>, form ((k+1)^n-1)/k %t A209120 Select[Prime[Range[100]], PrimeQ[(33^#-1)/32]&] %o A209120 (PARI) isok(n) = isprime((33^n-1)/32); \\ _Michel Marcus_, Mar 13 2016 %K A209120 hard,more,nonn %O A209120 1,1 %A A209120 _Robert Price_, Mar 05 2012 %E A209120 a(5) corresponds to a probable prime discovered by _Paul Bourdelais_, Dec 31 2018