OFFSET
1,6
COMMENTS
Note that the elements must be pairwise indivisible divisors of n.
Differs from A303838 at positions {1, 180, 210, ...}. For example, a(210) = 49, A303838(210) = 55. - Gus Wiseman, Apr 01 2019
LINKS
Gus Wiseman, Table of n, a(n) for n = 1..300
EXAMPLE
The a(30) = 8 subsets are: {30}, {2,15}, {3,10}, {5,6}, {6,10}, {6,15}, {10,15}, {2,3,5}.
MATHEMATICA
minim[s_]:=Complement[s, First/@Select[Tuples[s, 2], UnsameQ@@#&&SubsetQ@@#&]];
stableSets[u_, Q_]:=If[Length[u]==0, {{}}, With[{w=First[u]}, Join[stableSets[DeleteCases[u, w], Q], Prepend[#, w]&/@stableSets[DeleteCases[u, r_/; r==w||Q[r, w]||Q[w, r]], Q]]]];
Table[Length[minim[Select[Rest[stableSets[Divisors[n], Divisible]], LCM@@#==n&]]], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 19 2019
STATUS
approved