prove that the function
${2}^{n}.(2n+1)-1 $ from $ \Bbb{N}$x$\Bbb{N}\implies\Bbb{N}$
is invertible
I know that a function to be invertible must be injective and surjective, I am not sure how to calculate this since in this case I need a pair (x,y) since the function comes from $...