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 A239637 #11 Mar 14 2016 03:31:30 %S A239637 3,83,269,409,1759,11731 %N A239637 Numbers n such that (41^n - 1)/40 is prime. %C A239637 a(7) > 10^5. - _Robert Price_, Mar 22 2014 %H A239637 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 A239637 H. Lifchitz, <a href="http://www.primenumbers.net/Henri/us/MersFermus.htm">Mersenne and Fermat primes field</a> %H A239637 <a href="/index/Pri#primepop">Index to primes in various ranges</a>, form ((k+1)^n-1)/k %t A239637 Select[Prime[Range[100000]], PrimeQ[(41^#-1)/40]&] %o A239637 (PARI) isok(n) = isprime((41^n-1)/40); \\ _Michel Marcus_, Mar 13 2016 %K A239637 hard,more,nonn %O A239637 1,1 %A A239637 _Robert Price_, Mar 22 2014