OFFSET
1,6
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
EXAMPLE
The a(72)=10 sets are {72}, {8,9}, {8,18}, {8,36}, {9,24}, {18,24}, {24,36}, {6,8,9}, {8,9,12}, {8,12,18}.
MATHEMATICA
nn=50;
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[Select[Rest[stableSets[Divisors[n], Divisible]], LCM@@#===n&]], {n, 1, nn}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Apr 21 2017
STATUS
approved