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 A242797 #17 Aug 04 2020 12:16:44 %S A242797 19,53,167,3319,11257,34351,216551 %N A242797 Numbers n such that (45^n - 1)/44 is prime. %C A242797 a(7) > 10^5. %C A242797 Numbers corresponding to a(4)-a(6) are probable primes. %C A242797 All terms are prime. %H A242797 Harvey Dubner, <a href="http://dx.doi.org/10.1090/S0025-5718-1993-1185243-9">Generalized repunit primes</a>, Math. Comp., 61 (1993), 927-930. %H A242797 Henri Lifchitz, <a href="http://www.primenumbers.net/Henri/us/MersFermus.htm">Mersenne and Fermat primes field</a> %p A242797 A242797:=n->`if`(isprime((45^n - 1)/44), n, NULL); seq(A242797(n), n=1..100000); # _Wesley Ivan Hurt_, Apr 12 2014 %t A242797 Select[Prime[Range[100000]], PrimeQ[(45^# - 1)/44] &] %o A242797 (PARI) is(n)=ispseudoprime((45^n-1)/44) \\ _Charles R Greathouse IV_, Feb 20 2017 %Y A242797 Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034, A006035, A127995, A127996, A127997, A127998, A127999, A098438, A128002, A128003, A128004, A128005, A240765. %K A242797 hard,more,nonn %O A242797 1,1 %A A242797 _Robert Price_, May 22 2014 %E A242797 a(7)=216551 corresponds to a probable prime discovered by _Paul Bourdelais_, Aug 04 2020