%I #5 Oct 20 2017 15:42:12

%S 1,2,3,5,7,11,12,13,17,18,19,20,23,28,29,31,36,37,41,43,44,45,47,50,

%T 52,53,59,61,63,67,68,71,73,75,76,79,83,89,92,97,98,99,100,101,103,

%U 107,109,113,116,117,120,124,127,131,137,139,147,148,149,151,153

%N Numbers that can be written as a product of distinct squarefree numbers in exactly one way.

%C First differs from A212166 at a(128) = 363, A212166(128) = 360.

%e 360 is not in the sequence because it has two possible expressions: 2*3*6*10 or 2*6*30.

%t nn=300;

%t sqfacs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[sqfacs[n/d],Min@@#>d&]],{d,Select[Rest[Divisors[n]],SquareFreeQ]}]];

%t Select[Range[nn],Length[sqfacs[#]]===1&]

%Y Cf. A001055, A005117, A045778, A050320, A050326, A292432, A292444, A293243.

%K nonn

%O 1,2

%A _Gus Wiseman_, Oct 11 2017