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A366656 Number of divisors of 8^n+1.

%I A366656 #13 Jan 09 2024 18:46:29
%S A366656 2,3,4,8,4,12,16,12,8,20,48,24,16,12,64,64,8,48,64,24,16,64,64,24,32,
%T A366656 96,768,192,32,24,1536,24,8,256,512,1536,64,96,256,64,64,96,1024,48,
%U A366656 128,1280,256,96,128,96,8192,1024,32,48,1024,2304,256,192,256,192
%N A366656 Number of divisors of 8^n+1.
%H A366656 Max Alekseyev, <a href="/A366656/b366656.txt">Table of n, a(n) for n = 0..502</a>
%F A366656 a(n) = sigma0(8^n+1) = A000005(A062395(n)).
%F A366656 a(n) = A046798(3*n). - _Max Alekseyev_, Jan 09 2024
%e A366656 a(4)=4 because 8^4+1 has divisors {1, 17, 241, 4097}.
%p A366656 a:=n->numtheory[tau](8^n+1):
%p A366656 seq(a(n), n=0..100);
%t A366656 DivisorSigma[0, 8^Range[0,59] + 1] (* _Paul F. Marrero Romero_, Nov 12 2023 *)
%o A366656 (PARI) a(n) = numdiv(8^n+1);
%Y A366656 Cf. A062395, A000005, A057936, A274905, A366653, A366638, A366655, A366657, A366658.
%Y A366656 Cf. A046798, A366577, A366606, A366616, A366628, A366637, A366665, A344897, A366688, A366714.
%K A366656 nonn
%O A366656 0,1
%A A366656 _Sean A. Irvine_, Oct 15 2023