A327907 Numbers with more than one factorization into at factors > 1 with integer mean.

4, 8, 9, 12, 15, 16, 20, 21, 24, 25, 27, 28, 32, 33, 35, 36, 39, 40, 42, 44, 45, 48, 49, 50, 51, 52, 54, 55, 56, 57, 60, 63, 64, 65, 68, 69, 72, 75, 76, 77, 78, 80, 81, 84, 85, 87, 88, 91, 92, 93, 95, 96, 99, 100, 104, 105, 108, 110, 111, 112, 114, 115, 116

Offset

1,1

Links

Table of n, a(n) for n=1..63.

Example

There are 6 factorizations of 60 with integer mean, namely:
  (60)
  (2*30)
  (6*10)
  (3*4*5)
  (2*3*10)
  (2*2*3*5)
so 60 is in the sequence.

Mathematica

facs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facs[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Select[Range[100], Length[Select[facs[#], IntegerQ[Mean[#]]&]]>1&]

Crossrefs

Complement of A327906.

Positions of terms > 1 in A326622.

Cf. A001055, A051293, A067538, A078175, A123528/A123529, A316413, A326515, A326516, A326666, A326667, A326671.

Sequence in context: A037973 A044844 A145190 * A177713 A235992 A362006

Adjacent sequences: A327904 A327905 A327906 * A327908 A327909 A327910

Keyword

nonn

Author

Gus Wiseman, Sep 30 2019

Status

approved