Find the accumulation points of the set {2^n+1/k: n and k are positive integers}

The book gives the definition and then the author going on about how beautiful good proof is....without giving any examples of how to find them.

SO is the accumulation point going to be like a pair (n,k) or how should the answer look?

I know that if it were just for the set {1/k}, we would have the accumulation point be 0. The 2^n grows without limit though and so I don't know how that comes into play.