Ratio of productions of $\pi^{+}\pi^{-}$ atoms to free $\pi^{+}\pi^{-}$ pairs with account of the strong interaction in final states

The ratio of productions of pi+pi- atoms to free pi+pi- pairs is calculated with account of the strong interaction in final states. It is shown that this ratio is expressed via a squared ratio of the well-known Coulomb wave functions and thus can be calculated with a high accuracy.