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 A066727 #10 Oct 25 2024 09:38:03
%S A066727 0,1,2,3,2,5,2,3,2,3,2,5,2,3,2,3,2,7,2,3,2,3,2,5,2,3,2,3,2,17,2,3,2,3,
%T A066727 2,5,2,3,2,3,2,5,2,3,2,3,2,5,2,3,2,3,2,5,2,3,2,3,2,13,2,3,2,3,2,5,2,3,
%U A066727 2,3,2,5,2,3,2,3,2,5,2,3,2,3,2,5,2,3,2,3,2,7,2,3,2,3,2,5,2,3,2,3
%N A066727 Least factor of n^phi(n) - 1.
%C A066727 n^Phi(n)-1 is never prime. This sequence is an outgrowth of Euler's generalization to Fermat's little theorem.
%H A066727 Antti Karttunen, <a href="/A066727/b066727.txt">Table of n, a(n) for n = 1..65537</a>
%F A066727 For n > 1, a(n) = A020639(A066916(n)). - _Antti Karttunen_, Oct 24 2024
%t A066727 a = {}; Do[ a = Append[a, FactorInteger[ n^EulerPhi[n] - 1, FactorComplete -> False][[1, 1]]], {n, 1, 100}]; a
%o A066727 (PARI)
%o A066727 A020639(n) = if(1==n,n,forprime(p=2,,if(!(n%p),return(p))));
%o A066727 A066727(n) = if(1==n,0,A020639((n^eulerphi(n))-1)); \\ _Antti Karttunen_, Oct 24 2024
%Y A066727 Cf. A000010, A020639, A066916, A066699.
%K A066727 nonn
%O A066727 1,3
%A A066727 _Robert G. Wilson v_, Jan 15 2002