OFFSET
1,6
EXAMPLE
The a(144) = 17 set partitions:
(2*3*4*6) (2*8*9) (2*72) (144)
(2*6)*(3*4) (3*6*8) (3*48)
(2*3*24) (4*36)
(2*4*18) (6*24)
(2*6*12) (8*18)
(3*4*12) (9*16)
(2*6)*(12)
(3*4)*(12)
MATHEMATICA
strfacs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[strfacs[n/d], Min@@#>d&]], {d, Rest[Divisors[n]]}]];
sps[{}]:={{}}; sps[set:{i_, ___}]:=Join@@Function[s, Prepend[#, s]&/@sps[Complement[set, s]]]/@Cases[Subsets[set], {i, ___}];
Table[Length[Join@@Table[Select[sps[fac], SameQ@@Times@@@#&], {fac, strfacs[n]}]], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Oct 23 2018
STATUS
approved