OFFSET
1,6
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
a(n) is asymptotic to c*n with c = 0.36....
MATHEMATICA
Accumulate[Table[Boole[Mod[DivisorSigma[0, n], 3] == 1], {n, 1, 100}]] (* Amiram Eldar, Aug 29 2020 *)
PROG
(PARI) a(n)=sum(k=1, n, if(numdiv(k)%3-1, 0, 1))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Sep 07 2002
STATUS
approved