|
%I #9 Jan 09 2024 22:32:04
%S 2,6,4,24,8,32,12,96,8,96,16,512,16,144,64,768,32,160,16,4608,96,384,
%T 16,8192,128,192,64,9216,64,4096,8,6144,256,1536,1536,10240,64,384,
%U 512,73728,32,6144,32,24576,1024,384,64,262144,64,12288,256,147456,256
%N Number of divisors of 8^n-1.
%H Max Alekseyev, <a href="/A366652/b366652.txt">Table of n, a(n) for n = 1..500</a>
%F a(n) = sigma0(8^n-1) = A000005(A024088(n)).
%F a(n) = A046801(3*n). - _Max Alekseyev_, Jan 09 2024
%e a(5)=8 because 8^5-1 has divisors {1, 7, 31, 151, 217, 1057, 4681, 32767}.
%p a:=n->numtheory[tau](8^n-1):
%p seq(a(n), n=1..100);
%t DivisorSigma[0, 8^Range[100]-1]
%o (PARI) a(n) = numdiv(8^n-1);
%Y Cf. A024088, A000005, A057953, A059890, A366651, A366653, A366654.
%Y Cf. A046801, A366575, A366602, A366612, A366621, A366633, A366661, A070528, A366683, A366709.
%K nonn
%O 1,1
%A _Sean A. Irvine_, Oct 15 2023
|
