A230843 Cubefree numbers which in their canonical prime factorization have mutually distinct exponents.

1, 2, 3, 4, 5, 7, 9, 11, 12, 13, 17, 18, 19, 20, 23, 25, 28, 29, 31, 37, 41, 43, 44, 45, 47, 49, 50, 52, 53, 59, 61, 63, 67, 68, 71, 73, 75, 76, 79, 83, 89, 92, 97, 98, 99, 101, 103, 107, 109, 113, 116, 117, 121, 124, 127, 131, 137, 139, 147, 148, 149, 151, 153, 157, 163, 164, 167, 169, 171

Offset: 1

Author

Gerasimov Sergey, Oct 31 2013

Keywords

• nonn
• easy

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Intersection of A004709 and A130091.

Disjoint union of {1}, A000040, A001248 and A054753.

Programs

Mathematica

q[n_] := Max[(e = FactorInteger[n][[;; , 2]])] < 3 && Length @ Union[e] == Length[e]; Select[Range[200], q] (* Amiram Eldar, Feb 16 2021 *)