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A366652
Number of divisors of 8^n-1.
10
2, 6, 4, 24, 8, 32, 12, 96, 8, 96, 16, 512, 16, 144, 64, 768, 32, 160, 16, 4608, 96, 384, 16, 8192, 128, 192, 64, 9216, 64, 4096, 8, 6144, 256, 1536, 1536, 10240, 64, 384, 512, 73728, 32, 6144, 32, 24576, 1024, 384, 64, 262144, 64, 12288, 256, 147456, 256
OFFSET
1,1
LINKS
FORMULA
a(n) = sigma0(8^n-1) = A000005(A024088(n)).
a(n) = A046801(3*n). - Max Alekseyev, Jan 09 2024
EXAMPLE
a(5)=8 because 8^5-1 has divisors {1, 7, 31, 151, 217, 1057, 4681, 32767}.
MAPLE
a:=n->numtheory[tau](8^n-1):
seq(a(n), n=1..100);
MATHEMATICA
DivisorSigma[0, 8^Range[100]-1]
PROG
(PARI) a(n) = numdiv(8^n-1);
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 15 2023
STATUS
approved