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 A128004 #24 Oct 17 2017 13:01:49 %S A128004 3,7,401,449,109037 %N A128004 Numbers n such that (38^n - 1)/37 is prime. %C A128004 No other terms < 100000. - _Robert Price_, Dec 23 2011 %H A128004 H. 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 A128004 H. Lifchitz, <a href="http://www.primenumbers.net/Henri/us/MersFermus.htm">Mersenne and Fermat primes field</a> %H A128004 <a href="/index/Pri#primepop">Index to primes in various ranges</a>, form ((k+1)^n-1)/k %t A128004 Select[Prime[Range[100]],PrimeQ[(38^#-1)/37]&] %o A128004 (PARI) is(n)=ispseudoprime((38^n-1)/37) \\ _Charles R Greathouse IV_, Feb 17 2017 %K A128004 hard,more,nonn %O A128004 1,1 %A A128004 _Alexander Adamchuk_, Feb 11 2007 %E A128004 a(5) corresponds to a probable prime discovered by _Paul Bourdelais_, Oct 17 2017