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%I #8 Jan 20 2024 12:13:30
%S 4,10,12,36,8,60,16,84,64,80,16,864,8,160,96,384,16,640,16,1536,96,
%T 160,32,16128,32,80,1280,1152,32,3840,32,1728,384,80,128,18432,32,160,
%U 192,14336,32,7680,16,4608,2048,160,16,147456,256,640,768,1152,32,25600
%N Number of divisors of 7^n-1.
%H Max Alekseyev, <a href="/A366633/b366633.txt">Table of n, a(n) for n = 1..388</a>
%F a(n) = sigma0(7^n-1) = A000005(A024075(n)).
%e a(5)=8 because 7^5-1 has divisors {1, 2, 3, 6, 2801, 5602, 8403, 168061}.
%p a:=n->numtheory[tau](7^n-1):
%p seq(a(n), n=1..100);
%t DivisorSigma[0, 7^Range[100]-1]
%o (PARI) a(n) = numdiv(7^n-1);
%Y Cf. A024075, A000005, A057954, A059889, A074249, A218358, A366632, A366634, A366635.
%Y Cf. A046801, A366575, A366602, A366612, A366621, A366652, A366661, A070528, A366683, A366709.
%K nonn
%O 1,1
%A _Sean A. Irvine_, Oct 14 2023
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