A366637 - OEIS

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A366637

Number of divisors of 7^n+1.

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, 32, 24, 32, 64, 8, 512, 32, 16, 128, 48, 1024, 256, 16, 12, 256, 64, 64, 96, 512, 32, 2048, 96, 8, 64, 2048, 640, 128, 32, 64, 384, 3072, 256, 256, 96, 64, 512, 8, 48

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OFFSET

0,1

LINKS

Max Alekseyev, Table of n, a(n) for n = 0..387

FORMULA

a(n) = sigma0(7^n+1) = A000005(A034491(n)).

EXAMPLE

a(4)=4 because 7^4+1 has divisors {1, 2, 1201, 2402}.

MAPLE

a:=n->numtheory[tau](7^n+1):

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