OFFSET
1,1
LINKS
Max Alekseyev, Table of n, a(n) for n = 1..690
EXAMPLE
a(4)=10 because 3^4-1 has divisors {1, 2, 4, 5, 8, 10, 16, 20, 40, 80}.
MAPLE
a:=n->numtheory[tau](3^n-1):
seq(a(n), n=1..100);
MATHEMATICA
DivisorSigma[0, 3^Range[100]-1] (* Paolo Xausa, Oct 15 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 13 2023
STATUS
approved