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 A071190 #29 Feb 20 2018 22:53:29
%S A071190 1,3,2,7,3,3,2,5,13,3,3,7,7,3,3,31,3,13,5,7,2,3,3,5,31,7,5,7,5,3,2,7,
%T A071190 3,3,3,13,19,5,7,5,7,3,11,7,13,3,3,31,19,31,3,7,3,5,3,5,5,5,5,7,31,3,
%U A071190 13,127,7,3,17,7,3,3,3,13,37,19,31,7,3,7,5,31
%N A071190 Greatest prime factor of sum of divisors of n, for n >= 2; a(1) = 1.
%C A071190 a(n) is the greatest noncomposite factor of the sum of divisors of n. (Cf. A008578.) - _Omar E. Pol_, Feb 11 2018
%H A071190 Antti Karttunen, <a href="/A071190/b071190.txt">Table of n, a(n) for n = 1..10000</a>
%F A071190 a(n) = A006530(A000203(n)).
%t A071190 Table[FactorInteger[DivisorSigma[1,n]][[-1,1]],{n,80}] (* _Harvey P. Dale_, Nov 18 2014 *)
%o A071190 (PARI) a(n) = if (n==1, 1, my(f = factor(sigma(n))); f[#f~,1]); \\ _Michel Marcus_, Sep 21 2014
%Y A071190 Cf. A000203, A006530, A071188, A071189.
%K A071190 nonn
%O A071190 1,2
%A A071190 _Reinhard Zumkeller_, May 15 2002
%E A071190 Name clarified by _David A. Corneth_ and _Omar E. Pol_, Feb 11 2018