Hello,

I need to show that $\displaystyle (m,n) \mapsto 2^{m-1}(2n-1)$ is a bijection of $\displaystyle \mathbb{N} \times \mathbb{N} $ on $\displaystyle \mathbb{N}$

I think I need to show that the expression is both injective and surjective, but I am not sure how to do that.

Maybe a kind person can help me in some direction?

Thanks in advance.