Binary function

Let binary function $f(x,y)=(xy-1)/(x+y-1)$. There are infinite $(x,y)$ pairs of positive integers such that $f(x,y)$ is integer. For example, $f(1,1)=0$, $f(3,5)=2$, $f(5,17)=4$ and so on.

Find all such $(x,y)$ pairs for $1\le x\le y\le 50000000$.

Answer format: [number of pairs],[sum of x of all pairs], [sum of y of all pairs]

Example: 258,56772,129736 for $1\le x\le y\le 1000$.