OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
FORMULA
a(n) ~ c*n, where c = zeta(2) + zeta(3) (A347213). - Amiram Eldar, Sep 24 2023
EXAMPLE
a(1) = 1+1 = 2.
a(4) = 5+4 = 9.
a(8) = 11+9 = 20.
MATHEMATICA
Module[{nn=100, sf, cf, len}, sf=Select[Range[nn], SquareFreeQ]; cf=Select[ Range[ nn], Max[FactorInteger[#][[All, 2]]]<3&]; len=Min[ Length[ sf], Length[cf]]; Total/@Thread[{Take[sf, len], Take[cf, len]}]] (* Harvey P. Dale, Oct 01 2019 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Jan 19 2011
STATUS
approved