OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = A073185(n) - 1. - N. J. A. Sloane, Nov 30 2007
EXAMPLE
a(8) = 6 because the divisors of 8 are {1,2,4,8}, the cubefree divisors are 1, 2, 4 so we get a(8) = 2 + 4 = 6.
MATHEMATICA
scfd[n_]:=Total[Select[Divisors[n], Max[Transpose[FactorInteger[#]][[2]]]<3&]]; Array[scfd, 80]-1 (* Harvey P. Dale, Nov 30 2014 *)
f[p_, e_] := 1 + p + If[e > 1, p^2, 0]; a[1] = 0; a[n_] := -1 + Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Jul 09 2022 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Nov 29 2007
EXTENSIONS
Edited by N. J. A. Sloane, Nov 30 2007
STATUS
approved