A366683 - OEIS

%I #7 Jan 04 2024 16:10:51

%S 4,16,16,40,12,192,16,96,32,96,16,1920,16,128,96,448,8,1024,8,480,768,

%T 1024,32,18432,128,512,64,2560,16,9216,32,2048,512,256,192,20480,64,

%U 512,4096,4608,512,36864,16,10240,384,2048,32,1376256,128,4096,512,2560

%N Number of divisors of 11^n-1.

%H Max Alekseyev, <a href="/A366683/b366683.txt">Table of n, a(n) for n = 1..316</a>

%F a(n) = sigma0(11^n-1) = A000005(A024127(n)).

%e a(3)=16 because 11^3-1 has divisors {1, 2, 5, 7, 10, 14, 19, 35, 38, 70, 95, 133, 190, 266, 665, 1330}.

%p a:=n->numtheory[tau](11^n-1):

%p seq(a(n), n=1..100);

%t DivisorSigma[0, 11^Range[100]-1]

%o (PARI) a(n) = numdiv(11^n-1);

%Y Cf. A024127, A000005, A366681, A366682, A366684, A366685.

%Y Cf. A046801, A070528, A366709.

%K nonn

%O 1,1

%A _Sean A. Irvine_, Oct 16 2023