OFFSET
1,2
EXAMPLE
Sequence of trees begins:
1 o
2 (o)
4 (oo)
6 (o(o))
7 ((oo))
8 (ooo)
12 (oo(o))
16 (oooo)
19 ((ooo))
24 (ooo(o))
28 (oo(oo))
32 (ooooo)
38 (o(ooo))
42 (o(o)(oo))
48 (oooo(o))
52 (oo(o(o)))
53 ((oooo))
56 (ooo(oo))
57 ((o)(ooo))
64 (oooooo)
68 (oo((oo)))
74 (o(oo(o)))
84 (oo(o)(oo))
96 (ooooo(o))
MATHEMATICA
MGtree[n_]:=If[n===1, {}, MGtree/@Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
doQ[n_]:=Or[n===1, UnsameQ@@Length/@Cases[MGtree[n], {__}, {0, Infinity}]];
Select[Range[1000], doQ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 19 2018
STATUS
approved