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 A125571 #15 Dec 18 2024 22:00:16
%S A125571 3,13,5,11,7,29,3,7,11,15797,5,53,3,11,17,10949,7,
%T A125571 109912203092239643840221,3,43,23,461,5,11,3,109,5,59,7,
%U A125571 568972471024107865287021434301977158534824481,3,67,5,31,13,149,3,7,11,83,13,173,3,19,47
%N A125571 Least prime factor of Sum_{k=0..n-1} n^k.
%C A125571 The sequence of largest prime factors of numbers generated by the same sum is probably identical to sequence A006486, since (n^n - 1)/(1 + n^2 + ... + n^(n-1)) = n-1.
%H A125571 Chai Wah Wu, <a href="/A125571/b125571.txt">Table of n, a(n) for n = 2..178</a>
%e A125571 The sum 1 + 4 + 4^2 + 4^3 = 85 = 5 * 17 so the third term is 5.
%t A125571 Table[FactorInteger[Sum[n^k,{k,0,n-1}]][[1,1]],{n,2,46}] (* _James C. McMahon_, Dec 18 2024 *)
%o A125571 (PARI) a(n) = factor(sum(k=0, n-1, n^k))[1, 1]; \\ _Michel Marcus_, Aug 20 2013
%Y A125571 Cf. A006486.
%Y A125571 Least prime factors of A023037.
%K A125571 nonn
%O A125571 2,1
%A A125571 _Axel Harvey_, Jan 02 2007
%E A125571 More terms from _Michel Marcus_, Aug 20 2013