Lamb Shift Approximation for Elements up to 80 in a Very Simple Way

We suggest that the Lamb shift can be approximated by a very simple function that seems accurate enough for most experimental researchers working with elements where the relativistic effects of the electron are minimal, that is up to element 80 or so. Even if our new approximation does not show anything new in quantum chemistry per se, we think that it can be useful for experimental researchers and students of both quantum physics and chemistry; now everyone can calculate the Lamb shift on the back of an envelope.