OFFSET
0,1
LINKS
Max Alekseyev, Table of n, a(n) for n = 0..691
EXAMPLE
a(4)=126 because 3^4+1 has divisors {1, 2, 41, 82}.
MAPLE
a:=n->numtheory[sigma](3^n+1):
seq(a(n), n=0..100);
MATHEMATICA
DivisorSigma[1, 3^Range[0, 30]+1] (* Paolo Xausa, Oct 15 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 13 2023
STATUS
approved