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 A245237 #22 Mar 03 2025 12:30:45 %S A245237 19,269,349,383,1303,15031,200443,343901 %N A245237 Numbers k such that (48^k - 1)/47 is prime. %C A245237 a(7) > 10^5. %C A245237 All terms are prime. %H A245237 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 A245237 Henri Lifchitz, <a href="http://www.primenumbers.net/Henri/us/MersFermus.htm">Mersenne and Fermat primes field</a> %p A245237 A245237:=n->`if`(isprime((48^n - 1)/47), n, NULL); seq(A245237(n), n=1..100000); # _Wesley Ivan Hurt_, Apr 12 2014 %t A245237 Select[Prime[Range[100000]], PrimeQ[(48^# - 1)/47] &] %o A245237 (PARI) is(n)=ispseudoprime((48^n-1)/47) \\ _Charles R Greathouse IV_, Jun 06 2017 %Y A245237 Cf. A028491, A004061, A004062, A004063, A004023, A005808, A004064, A016054, A006032, A006033, A006034, A006035, A127995, A127996, A127997, A127998, A127999, A098438, A128002, A128003, A128004, A128005, A240765, A242797, A243279. %K A245237 hard,more,nonn %O A245237 1,1 %A A245237 _Robert Price_, Jul 14 2014 %E A245237 a(7) corresponds to a probable prime discovered by _Paul Bourdelais_, Aug 04 2020 %E A245237 a(8) from _Paul Bourdelais_, Mar 03 2025