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 A366575 #12 Jan 05 2024 19:07:11
%S A366575 2,4,4,10,6,16,4,24,8,24,8,80,4,16,24,112,8,128,8,180,16,64,8,384,24,
%T A366575 16,64,160,16,768,16,256,32,128,48,1280,8,64,96,864,16,768,8,640,384,
%U A366575 32,32,14336,128,384,64,160,16,4096,128,1536,128,256,8,23040,8
%N A366575 Number of divisors of 3^n - 1.
%H A366575 Max Alekseyev, <a href="/A366575/b366575.txt">Table of n, a(n) for n = 1..690</a>
%F A366575 a(n) = sigma0(3^n-1) = A000005(A024023).
%e A366575 a(4)=10 because 3^4-1 has divisors {1, 2, 4, 5, 8, 10, 16, 20, 40, 80}.
%p A366575 a:=n->numtheory[tau](3^n-1):
%p A366575 seq(a(n), n=1..100);
%t A366575 DivisorSigma[0,3^Range[100]-1] (* _Paolo Xausa_, Oct 15 2023 *)
%Y A366575 Cf. A024023, A000005, A046801, A133801, A295500, A366576.
%Y A366575 Cf. A046801, A366602, A366612, A366621, A366633, A366652, A366661, A070528, A366683, A366709.
%K A366575 nonn
%O A366575 1,1
%A A366575 _Sean A. Irvine_, Oct 13 2023