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 A247230 #12 Dec 14 2014 15:11:25
%S A247230 3,13,71,55987,12207031,16148168401,50544702849929377,
%T A247230 109912203092239643840221,26552618219228090162977481,
%U A247230 582595509837473004489665028935473297399,568972471024107865287021434301977158534824481,4673016293261684390446904937094157950067612234753
%N A247230 Maximum of the greatest prime factors of (i^prime(n)-1)/(i-1), when i runs through all integers in [2, prime(n)].
%C A247230 If in the definition "maximum" is replaced with "minimum," then we obtain A247229.
%F A247230 a(n)==1 (mod prime(n)).
%o A247230 (PARI) a(n) = {maxi = 0; p = prime(n); for (i=2, p, f = factor((i^p-1)/(i-1)); gpf = f[#f~, 1]; if (! maxi, maxi = gpf, maxi = max(maxi, gpf));); maxi;} \\ _Michel Marcus_, Dec 09 2014
%Y A247230 Cf. A247216, A247229.
%K A247230 nonn
%O A247230 1,1
%A A247230 _Vladimir Shevelev_, Nov 27 2014
%E A247230 More terms from _Peter J. C. Moses_, Nov 27 2014