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 A032505 #23 Jul 08 2025 19:41:15 %S A032505 279,415,711,115807,241071 %N A032505 Numbers n such that 257*2^n+1 is prime. %H A032505 Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</a> %H A032505 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 A032505 Wilfrid Keller, <a href="http://www.prothsearch.com/riesel2.html">List of primes k.2^n - 1 for k < 300</a> %H A032505 <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 A032505 (PARI) is(n)=ispseudoprime(257*2^n+1) \\ _Charles R Greathouse IV_, Jun 07 2017 %K A032505 nonn,hard %O A032505 1,1 %A A032505 _N. J. A. Sloane_ %E A032505 One more term (from the Ballinger-Keller web page) from _M. F. Hasler_, Apr 18 2007