OFFSET
1,4
EXAMPLE
The factorizations of 2, 4, 12, 24, 30, 36, 48, and 60 that are constant or whose factors are relatively prime:
2 4 12 24 30 36 48 60
2*2 3*4 3*8 5*6 4*9 3*16 3*20
2*2*3 2*3*4 2*15 6*6 2*3*8 4*15
2*2*2*3 3*10 2*2*9 3*4*4 5*12
2*3*5 2*3*6 2*2*3*4 2*5*6
3*3*4 2*2*2*2*3 3*4*5
2*2*3*3 2*2*15
2*3*10
2*2*3*5
MATHEMATICA
facs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facs[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Table[Length[Select[facs[n], #=={}||Length[Union[#]]==1||GCD@@#==1&]], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Sep 22 2019
STATUS
approved