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 A162964 #19 Nov 20 2017 05:36:02
%S A162964 1,15,24,60,120,360,168,480,168,360,360,1170,480,1512,1512,210,360,
%T A162964 1170,728,1680,576,480,1512,4800,210,1680,1344,3276,992,2016,576,1651,
%U A162964 1560,3276,1560,1512,1512,4800,3276,4064,1680,5952,1560,5040,4800,2016,1560,5040
%N A162964 a(n) = sigma(sigma(sigma(sigma(sigma(n))))).
%H A162964 Antti Karttunen, <a href="/A162964/b162964.txt">Table of n, a(n) for n = 1..16384</a>
%H A162964 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A162964 a(n) = A000203(A000203(A000203(A000203(A000203(n))))).
%p A162964 with(numtheory); f:=n->sigma(sigma(sigma(sigma(sigma(n))))); [seq(f(n),n=1..100)];
%t A162964 Table[Nest[DivisorSigma[1,#]&,n,5],{n,50}] (* _Harvey P. Dale_, Apr 19 2013 *)
%o A162964 (PARI) A162964(n) = sigma(sigma(sigma(sigma(sigma(n))))); \\ _Antti Karttunen_, Nov 18 2017
%Y A162964 Cf. A000203, A129076, A066971, A051027.
%Y A162964 Cf. also A049107.
%K A162964 nonn
%O A162964 1,2
%A A162964 _Jaroslav Krizek_, Jul 19 2009
%E A162964 More terms from _N. J. A. Sloane_, Mar 20 2010