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 A062586 #20 Jul 04 2021 08:43:16 %S A062586 5,17,109,1979,6899,7331,18661,79621,81649 %N A062586 Numbers k such that 20^k - 19^k is prime. %C A062586 Terms k > 1000 may correspond to (unproven) strong pseudoprimes. %H A062586 Henri Lifchitz and Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=20%5Ep-19%5Ep">Top probable primes of the form 20^p-19^p</a> %o A062586 (PARI) is(n)=ispseudoprime(20^n-19^n) \\ _Charles R Greathouse IV_, Jun 12 2017 %Y A062586 Cf. A000043, A057468, A059801, A059802, A062572-A062666. %K A062586 nonn,hard %O A062586 1,1 %A A062586 _Mike Oakes_, May 18 2001, May 19 2001 %E A062586 a(7)-a(9) found by _Jean-Louis Charton_ in February and March 2011 %E A062586 Edited by _M. F. Hasler_, Sep 16 2013