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%I #12 Jan 20 2024 12:22:10
%S 2,4,6,8,4,16,24,16,8,16,32,16,32,16,12,64,8,8,48,16,16,128,48,8,16,
%T 32,24,32,64,8,512,32,16,128,48,1024,256,16,12,256,64,64,96,512,32,
%U 2048,96,8,64,2048,640,128,32,64,384,3072,256,256,96,64,512,8,48
%N Number of divisors of 7^n+1.
%H Max Alekseyev, <a href="/A366637/b366637.txt">Table of n, a(n) for n = 0..387</a>
%F a(n) = sigma0(7^n+1) = A000005(A034491(n)).
%e a(4)=4 because 7^4+1 has divisors {1, 2, 1201, 2402}.
%p a:=n->numtheory[tau](7^n+1):
%p seq(a(n), n=0..100);
%t DivisorSigma[0, 7^Range[0, 62] + 1] (* _Paul F. Marrero Romero_, Oct 16 2023 *)
%o (PARI) a(n) = numdiv(7^n+1);
%Y Cf. A034491, A000005, A057937, A227575, A366633, A366636, A366638, A366639.
%Y Cf. A046798, A366577, A366606, A366616, A366628, A366656, A366665, A344897, A366688, A366714.
%K nonn
%O 0,1
%A _Sean A. Irvine_, Oct 15 2023
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