A366656 - OEIS

%I #13 Jan 09 2024 18:46:29

%S 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 96,768,192,32,24,1536,24,8,256,512,1536,64,96,256,64,64,96,1024,48,

%U 128,1280,256,96,128,96,8192,1024,32,48,1024,2304,256,192,256,192

%N Number of divisors of 8^n+1.

%H Max Alekseyev, <a href="/A366656/b366656.txt">Table of n, a(n) for n = 0..502</a>

%F a(n) = sigma0(8^n+1) = A000005(A062395(n)).

%F a(n) = A046798(3*n). - _Max Alekseyev_, Jan 09 2024

%e a(4)=4 because 8^4+1 has divisors {1, 17, 241, 4097}.

%p a:=n->numtheory[tau](8^n+1):

%p seq(a(n), n=0..100);

%t DivisorSigma[0, 8^Range[0,59] + 1] (* _Paul F. Marrero Romero_, Nov 12 2023 *)

%o (PARI) a(n) = numdiv(8^n+1);

%Y Cf. A062395, A000005, A057936, A274905, A366653, A366638, A366655, A366657, A366658.

%Y Cf. A046798, A366577, A366606, A366616, A366628, A366637, A366665, A344897, A366688, A366714.

%K nonn

%O 0,1

%A _Sean A. Irvine_, Oct 15 2023