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 A247216 #21 Mar 25 2017 06:39:10
%S A247216 3,13,31,55987,12207031,16148168401,50544702849929377,
%T A247216 109912203092239643840221,11111111111111111111111,
%U A247216 7369130657357778596659,568972471024107865287021434301977158534824481,388230138454493
%N A247216 Maximum of the smallest prime factors of (i^prime(n)-1)/(i-1), when i runs through all integers in [2, prime(n)].
%C A247216 If in the definition "maximum" is replaced with "minimum," then we obtain A035095 (see comment there).
%F A247216 a(n) == 1 (mod prime(n)).
%p A247216 with(numtheory):
%p A247216 a:= n-> max(seq(min(factorset(
%p A247216 (i^ithprime(n)-1)/(i-1))[]), i=2..ithprime(n))):
%p A247216 seq(a(n), n=1..10); # _Alois P. Heinz_, Dec 06 2014
%t A247216 a[n_] := Max[Table[Min[FactorInteger[(i^Prime[n]-1)/(i-1)][[All, 1]]], {i, 2, Prime[n]}]];
%t A247216 Table[a[n], {n, 1, 12}] (* _Jean-François Alcover_, Mar 25 2017, after _Alois P. Heinz_ *)
%Y A247216 Cf. A020639, A035095.
%K A247216 nonn
%O A247216 1,1
%A A247216 _Vladimir Shevelev_, Nov 26 2014
%E A247216 More terms from _Peter J. C. Moses_, Nov 26 2014