The Relativistic Rydberg’s Formula in Greater Depth and for Any Atom

K. Suto has recently pointed out an interesting relativistic extension of Rydberg’s formula. Here we also discuss Rydberg’s formula, and offer additional evidence on how one can easily see that it is non-relativistic and therefore a good approximation, at best, when . We also extend the Suto formula to hold for any atom and examine the formula in detail.