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 A353753 #10 May 08 2022 15:39:31
%S A353753 0,0,0,0,0,0,0,0,0,2,0,0,0,0,4,0,0,0,0,0,8,4,0,0,0,0,0,0,0,16,0,0,8,6,
%T A353753 8,0,0,0,12,8,0,16,0,0,0,8,0,0,0,0,12,6,0,0,16,0,16,8,0,24,0,0,0,0,12,
%U A353753 32,0,0,16,32,0,0,0,0,0,0,16,24,0,0,0,12,0,48,24,0,16,16,0,24,24,0,32,16,16,0,0,36
%N A353753 a(n) = phi(sigma(n)) - Product_{p^e||n} phi(sigma(p^e)), where n = Product_{p^e||n}, with each p^e the maximal power of prime p that divides n.
%H A353753 Antti Karttunen, <a href="/A353753/b353753.txt">Table of n, a(n) for n = 1..65537</a>
%H A353753 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A353753 a(n) = A062401(n) - A353752(n).
%o A353753 (PARI)
%o A353753 A062401(n) = eulerphi(sigma(n));
%o A353753 A353753(n) = { my(f = factor(n)); A062401(n)-prod(k=1, #f~, A062401(f[k, 1]^f[k, 2])); };
%Y A353753 Cf. A000010, A000203, A062401, A353752, A353754, A353755.
%Y A353753 Cf. A336547 (positions of 0's), A336548 (positions of terms > 0).
%Y A353753 Cf. also A353803.
%K A353753 nonn
%O A353753 1,10
%A A353753 _Antti Karttunen_, May 08 2022