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 A055033 #11 Jul 24 2024 18:11:21
%S A055033 1,4,5,6,12,20,9,10,18,30,20,30,24,36,36,18,30,72,30,72,33,50,36,50,
%T A055033 42,96,40,54,72,90,33,48,68,84,68,78,60,120,72,84,96,132,60,120,120,
%U A055033 90,68,90,78,168,90,144,84,160,90,90,102,180,120,216,96
%N A055033 a(n) = usigma(usigma(n)), where usigma(n) is the sum of unitary divisors of n (A034448).
%H A055033 Nathaniel Johnston, <a href="/A055033/b055033.txt">Table of n, a(n) for n = 1..10000</a>
%F A055033 a(n) = A034448(A034448(n)). - _Amiram Eldar_, Jul 24 2024
%t A055033 usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); usigma[1] = 1; a[n_] := usigma[usigma[n]]; Array[a, 100] (* _Amiram Eldar_, Jul 24 2024 *)
%o A055033 (PARI) usigma(n) = {my(f = factor(n)); prod(i = 1, #f~, 1 + f[i, 1]^f[i, 2]);}
%o A055033 a(n) = usigma(usigma(n)); \\ _Amiram Eldar_, Jul 24 2024
%Y A055033 Cf. A034448, A051027, A061765, A064012.
%K A055033 nonn,easy
%O A055033 1,2
%A A055033 _N. J. A. Sloane_, Oct 30 2001