OFFSET
1,4
LINKS
EXAMPLE
The a(90) = 7 factorizations together with the corresponding multiset partitions of {1,2,2,3}:
(2*3*3*5) {{1},{2},{2},{3}}
(2*5*9) {{1},{3},{2,2}}
(2*45) {{1},{2,2,3}}
(3*3*10) {{2},{2},{1,3}}
(5*18) {{3},{1,2,2}}
(9*10) {{2,2},{1,3}}
(90) {{1,2,2,3}}
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||CoprimeQ@@Union[#]&]], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Sep 22 2019
STATUS
approved