OFFSET
1,2
MATHEMATICA
facs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facs[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Join@@Position[Table[Sum[(-1)^Length[f], {f, facs[n]}], {n, 100}], _Integer?(Abs[#]>0&)]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Sep 15 2018
STATUS
approved