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 A249509 #16 Apr 03 2023 10:36:13 %S A249509 2,3,5,7,25,19,20,42,96,190,134,164,650,852,1455,2765,2480,3960,5464, %T A249509 6694,17206,13118,13680,28481,27445,28821,101696,116232,142083,187376, %U A249509 250118,1200007 %N A249509 Smallest number k >= A000043(n) such that k*A000668(n)*(k*A000668(n)+1)-1 is prime. %C A249509 a(34) = 1200007. %C A249509 A000043(34) = 756839. %C A249509 A000668(34) = 2^756839-1. %C A249509 1200007*(2^756839-1)*(1200007*(2^756839-1)+1)-1 is a 455675 digits certified prime using PFGW. %H A249509 Chris K. Caldwell, The List of Largest Known Primes, <a href="https://t5k.org/primes/page.php?id=118696">Prime corresponding to a(34)</a> %Y A249509 Cf. A000043, A000668, A137908, A137909. %K A249509 nonn %O A249509 1,1 %A A249509 _Pierre CAMI_, Oct 30 2014