A324928 Matula-Goebel numbers of rooted trees of depth 3.

5, 10, 13, 15, 17, 20, 23, 25, 26, 30, 34, 35, 37, 39, 40, 43, 45, 46, 50, 51, 52, 60, 61, 65, 67, 68, 69, 70, 73, 74, 75, 78, 80, 85, 86, 89, 90, 91, 92, 95, 100, 102, 103, 104, 105, 107, 111, 115, 117, 119, 120, 122, 125, 129, 130, 134, 135, 136, 138, 140

Offset: 1

Author

Gus Wiseman, Mar 21 2019

Keywords

• nonn

Comments

Numbers n such that A109082(n) = 3.

Examples

			The sequence of all rooted trees of depth 3 together with their Matula-Goebel numbers begins:
   5: (((o)))
  10: (o((o)))
  13: ((o(o)))
  15: ((o)((o)))
  17: (((oo)))
  20: (oo((o)))
  23: (((o)(o)))
  25: (((o))((o)))
  26: (o(o(o)))
  30: (o(o)((o)))
  34: (o((oo)))
  35: (((o))(oo))
  37: ((oo(o)))
  39: ((o)(o(o)))
  40: (ooo((o)))
  43: ((o(oo)))
  45: ((o)(o)((o)))
  46: (o((o)(o)))
  50: (o((o))((o)))
  51: ((o)((oo)))
  52: (oo(o(o)))
  60: (oo(o)((o)))
		

Crossrefs

Cf. A000081, A003963, A007097, A102378, A318400, A324927, A324930.

Programs

Mathematica

Select[Range[100],Length[NestWhileList[Times@@PrimePi/@FactorInteger[#][[All,1]]&,#,#>1&]]-1==3&]