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A366577
Number of divisors of 3^n+1.
11
2, 3, 4, 6, 4, 6, 8, 6, 8, 24, 12, 12, 8, 6, 16, 48, 4, 24, 16, 12, 8, 72, 16, 6, 64, 24, 16, 96, 16, 24, 48, 12, 4, 96, 16, 24, 16, 24, 16, 192, 32, 12, 128, 6, 32, 768, 16, 24, 16, 24, 128, 384, 16, 12, 32, 96, 64, 192, 16, 12, 128, 12, 32, 4608, 4, 24, 64
OFFSET
0,1
LINKS
FORMULA
a(n) = sigma0(3^n+1) = A000005(A034472(n)).
EXAMPLE
a(4)=4 because 3^4+1 has divisors {1, 2, 41, 82}.
MAPLE
a:=n->numtheory[tau](3^n+1):
seq(a(n), n=0..100);
MATHEMATICA
DivisorSigma[0, 3^Range[0, 100]+1] (* Paolo Xausa, Oct 15 2023 *)
PROG
(PARI) a(n) = numdiv(3^n+1); \\ Michel Marcus, Oct 14 2023
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 13 2023
STATUS
approved