Is there a recursive relation, like one for geometric series
$$G_n=1+x+x^2+...+x^n$$ $$G_{n+1}=1+xG_n$$
For the taylor expansion of the exponential function?
$$e^x_n=\sum\limits_{i=0}^n\frac{x^i}{i!}$$
Omitting of course the trivial case
$$e^x_{n+1}=e_n^x+\frac{x^{n+1}}{(n+1)!}$$
Or perhaps expressing the entire power expansion by means of other functions?
You might like the following integral representation
but probably you are looking for something different.