OFFSET
1,1
COMMENTS
Contains p^7 for all primes p.
EXAMPLE
The 15 factorizations and 5 strict factorizations of 2187:
(2187) (2187)
(27*81) (27*81)
(3*729) (3*729)
(9*243) (9*243)
(3*9*81) (3*9*81)
(9*9*27)
(3*27*27)
(3*3*243)
(3*9*9*9)
(3*3*3*81)
(3*3*9*27)
(3*3*3*9*9)
(3*3*3*3*27)
(3*3*3*3*3*9)
(3*3*3*3*3*3*3)
MATHEMATICA
facsm[n_]:=facsm[n]=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facsm[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Select[Range[100000], 3==Length[facsm[#]]/Length[Select[facsm[#], UnsameQ@@#&]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 12 2020
EXTENSIONS
a(7)-(10) from Alois P. Heinz, Jan 17 2020
a(11)-a(29) from Giovanni Resta, Jan 20 2020
STATUS
approved