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 A032363 #30 Aug 30 2020 02:30:10 %S A032363 2,4,7,16,19,20,22,26,40,44,46,47,50,56,59,64,92,175,215,275,407,455, %T A032363 1076,1090,3080,3322,6419,7639,19360,30500,38770,44164,50696,114760, %U A032363 117784,153847,160874,178739,379880,405514,672007,974752,1164664,1476347,2218064 %N A032363 Numbers k such that 27*2^k+1 is prime. %H A032363 Jeppe Stig Nielsen, <a href="/A032363/b032363.txt">Table of n, a(n) for n = 1..47</a> %H A032363 Ray Ballinger and Wilfrid Keller, <a href="http://www.prothsearch.com/riesel1.html">List of primes k.2^n + 1 for k < 300</a> %H A032363 Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</a> %H A032363 Y. Gallot, <a href="http://www.utm.edu/research/primes/programs/gallot/index.html">Proth.exe: Windows Program for Finding Large Primes</a> %H A032363 Wilfrid Keller, <a href="http://www.prothsearch.com/riesel2.html">List of primes k.2^n - 1 for k < 300</a> %H A032363 <a href="/index/Pri#riesel">Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime</a> %o A032363 (PARI) is(n)=ispseudoprime(27*2^n+1) \\ _Charles R Greathouse IV_, Jun 06 2017 %Y A032363 Cf. A050539 = 27*2^n-1 is prime. %K A032363 nonn,hard %O A032363 1,1 %A A032363 _James R. Buddenhagen_ %E A032363 More terms from _Hugo Pfoertner_, Jun 20 2003 %E A032363 More terms from _Hugo Pfoertner_, Aug 17 2004 %E A032363 Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), _Joerg Arndt_, Apr 07 2013