TITLE: Examples of abelian group with some property
QUESTION [5 upvotes]: Somebody told me there exists a torsion-free abelian group $G$, such that $G$ is isomorphic to $G\oplus G\oplus G$, but $G$ is not isomorphic to $G\oplus G$. But he does not tell me such a concrete example, since he dose not know too.

I do not know if there is a well-known example about this.
  Could anyone give such an example? Or any references?

Thanks.

REPLY [6 votes]: As Geoff Robinson mentioned, you may find it here
P.S. I don't know why I cannot write a comment now. Something is wrong with my PC!