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Number of divisors of 6^n+1.
9

%I #7 Jan 07 2024 12:00:43

%S 2,2,2,4,2,8,8,12,4,8,8,4,4,16,8,32,8,8,64,8,8,48,16,8,16,16,16,32,32,

%T 16,512,4,8,64,8,1536,32,16,8,512,32,16,128,4,8,128,32,4,128,64,64,

%U 256,16,32,1024,192,64,128,8,4,64,8,4,768,8,256,2048,32,32

%N Number of divisors of 6^n+1.

%H Max Alekseyev, <a href="/A366628/b366628.txt">Table of n, a(n) for n = 0..420</a>

%F a(n) = sigma0(6^n+1) = A000005(A062394(n)).

%e a(3)=4 because 6^3+1 has divisors {1, 7, 31, 217}.

%p a:=n->numtheory[tau](6^n+1):

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

%o (PARI) a(n) = numdiv(6^n+1);

%Y Cf. A062394, A000005, A057938, A366621, A366627, A366629, A366630, A366670.

%Y Cf. A046798, A366577, A366606, A366616, A366637, A366656, A366665, A344897, A366688, A366714.

%K nonn

%O 0,1

%A _Sean A. Irvine_, Oct 14 2023