OFFSET
1,2
LINKS
T. D. Noe, Table of n, a(n) for n=1..1000
FORMULA
a(n)=Length[Union[Table[DivisorSigma[1, w], {w, 1, n}]]]
PROG
(Python)
from sympy import divisor_sigma
def A061069(n): return len({divisor_sigma(i) for i in range(1, n+1)}) # Chai Wah Wu, Sep 08 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, May 28 2001
STATUS
approved