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 A366633 #8 Jan 20 2024 12:13:30
%S A366633 4,10,12,36,8,60,16,84,64,80,16,864,8,160,96,384,16,640,16,1536,96,
%T A366633 160,32,16128,32,80,1280,1152,32,3840,32,1728,384,80,128,18432,32,160,
%U A366633 192,14336,32,7680,16,4608,2048,160,16,147456,256,640,768,1152,32,25600
%N A366633 Number of divisors of 7^n-1.
%H A366633 Max Alekseyev, <a href="/A366633/b366633.txt">Table of n, a(n) for n = 1..388</a>
%F A366633 a(n) = sigma0(7^n-1) = A000005(A024075(n)).
%e A366633 a(5)=8 because 7^5-1 has divisors {1, 2, 3, 6, 2801, 5602, 8403, 168061}.
%p A366633 a:=n->numtheory[tau](7^n-1):
%p A366633 seq(a(n), n=1..100);
%t A366633 DivisorSigma[0, 7^Range[100]-1]
%o A366633 (PARI) a(n) = numdiv(7^n-1);
%Y A366633 Cf. A024075, A000005, A057954, A059889, A074249, A218358, A366632, A366634, A366635.
%Y A366633 Cf. A046801, A366575, A366602, A366612, A366621, A366652, A366661, A070528, A366683, A366709.
%K A366633 nonn
%O A366633 1,1
%A A366633 _Sean A. Irvine_, Oct 14 2023