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 A366665 #14 Jan 08 2024 21:00:14
%S A366665 2,4,4,8,8,12,8,16,4,16,8,16,64,16,16,48,4,16,16,16,32,128,32,16,16,
%T A366665 128,16,32,64,16,128,32,4,64,32,384,256,32,64,128,32,32,1024,128,64,
%U A366665 384,16,16,64,512,64,256,128,64,512,192,512,512,32,8,2048,64,16
%N A366665 Number of divisors of 9^n+1.
%H A366665 Max Alekseyev, <a href="/A366665/b366665.txt">Table of n, a(n) for n = 0..345</a>
%F A366665 a(n) = sigma0(9^n+1) = A000005(A062396(n)).
%F A366665 a(n) = A366577(2*n). - _Max Alekseyev_, Jan 08 2024
%e A366665 a(2)=4 because 9^2+1 has divisors {1, 2, 41, 82}.
%p A366665 a:=n->numtheory[tau](9^n+1):
%p A366665 seq(a(n), n=0..100);
%t A366665 DivisorSigma[0, 9^Range[0,62] + 1] (* _Paul F. Marrero Romero_, Nov 13 2023 *)
%o A366665 (PARI) a(n) = numdiv(9^n+1);
%Y A366665 Cf. A062396, A000005, A057935, A366661, A366664, A366666, A366667.
%Y A366665 Cf. A046798, A366577, A366606, A366616, A366628, A366637, A366656, A344897, A366688, A366714.
%K A366665 nonn
%O A366665 0,1
%A A366665 _Sean A. Irvine_, Oct 15 2023