This may be more than 15 symbols, but 
$$
f(x)= x + \frac{1}{1+((x-1+\delta)^{2n/(2n-1)}}
$$
where $\delta>0$ is small and $n$ is large. For $n=2$ and $\delta=1/10$ it looks like this:

![alt text][1]


  [1]: http://www.math.hawaii.edu/~bjoern/Teaching/MO.jpg