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 A036453 #25 Apr 16 2022 21:33:01
%S A036453 1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
%T A036453 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
%U A036453 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2
%N A036453 a(n) = d(d(d(d(d(n))))), the 5th iterate of the number-of-divisors function d = A000005, with initial value n.
%C A036453 The iterated d function rapidly converges to fixed point 2. In the 5th iterated d-sequence, the first term different from the fixed point 2 appears at n = 5040. The 6th and further iterated sequences have very long initial segment of 2's. In the 6th one the first non-stationary term is a(293318625600) = 3. In such sequences any large value occurs infinite many times and constructible.
%C A036453 Differs from A007395 for n = 1, 5040, 7920, 8400, 9360, 10080, 10800, etc. - _R. J. Mathar_, Oct 20 2008
%H A036453 Charles R Greathouse IV, <a href="/A036453/b036453.txt">Table of n, a(n) for n = 1..10000</a>
%e A036453 E.g., n = 96 and its successive iterates are 12, 6, 4, 3 and 2. The 5th term is a(96) = 2 is stationary (fixed).
%t A036453 Table[Nest[DivisorSigma[0,#]&,n,5],{n,110}] (* _Harvey P. Dale_, Jun 18 2021 *)
%o A036453 (PARI) a(n)=my(d=numdiv);d(d(d(d(d(n))))) \\ _Charles R Greathouse IV_, Apr 07 2012
%Y A036453 Cf. A000005, A010553, A036450, A036452.
%K A036453 nonn
%O A036453 1,2
%A A036453 _Labos Elemer_
%E A036453 Previous Mathematica program replaced by _Harvey P. Dale_, Jun 18 2021