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 A032418 #37 Apr 06 2020 02:58:24 %S A032418 3,27,39,83,203,395,467,875,1979,6939,13623,22835,56307,81839,197783, %T A032418 224879,261147,523283,533043,2457639 %N A032418 Numbers n such that 137 * 2^n + 1 is a prime. %H A032418 Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</a> %H A032418 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 A032418 Wilfrid Keller, <a href="http://www.prothsearch.com/riesel2.html">List of primes k.2^n - 1 for k < 300</a> %H A032418 <a href="/index/Pri#riesel">Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is a prime</a> %e A032418 137 * 2^3 + 1 = 1097 is a prime so 3 is in the sequence. %e A032418 137 * 2^5 + 1 = 4385 = 5 * 877, so 5 is not in the sequence. %t A032418 Select[Range[1000], PrimeQ[137 2^# + 1] &] (* _Alonso del Arte_, Apr 06 2020 *) %K A032418 nonn,hard %O A032418 1,1 %A A032418 _James R. Buddenhagen_ %E A032418 3 more terms sent by _Jud McCranie_, Jan 15 2000 and May 03 2000 %E A032418 One more term from _Jud McCranie_, Jun 12 2004 %E A032418 533043 from _Jud McCranie_, Oct 06 2004 %E A032418 a(20) = 2457639 from _Jeppe Stig Nielsen_, Apr 04 2020