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 A366621 #10 Apr 15 2025 22:21:41
%S A366621 2,4,4,8,6,16,4,16,16,48,8,128,8,48,48,64,32,128,8,384,16,32,32,512,
%T A366621 32,128,64,384,4,1536,8,512,64,256,96,8192,64,64,64,3072,8,768,32,512,
%U A366621 1536,256,16,8192,32,512,512,2048,16,2048,96,12288,128,64,16
%N A366621 Number of divisors of 6^n-1.
%H A366621 Max Alekseyev, <a href="/A366621/b366621.txt">Table of n, a(n) for n = 1..430</a>
%F A366621 a(n) = sigma0(6^n-1) = A000005(A024062(n)).
%e A366621 a(4)=8 because 6^4-1 has divisors {1, 5, 7, 35, 37, 185, 259, 1295}.
%p A366621 a:=n->numtheory[tau](6^n-1):
%p A366621 seq(a(n), n=1..100);
%t A366621 DivisorSigma[0, 6^Range[100]-1]
%o A366621 (PARI) a(n) = numdiv(6^n-1);
%Y A366621 Cf. A024062, A000005, A057955, A059888, A274907, A366613, A366620, A366622, A366623.
%Y A366621 Cf. A046801, A366575, A366602, A366612, A366633, A366652, A366661, A070528, A366683, A366709.
%K A366621 nonn
%O A366621 1,1
%A A366621 _Sean A. Irvine_, Oct 14 2023