This may be more than 15 symbols, but $$ f(x)= x + \frac{1}{1+(x+\delta-1)^{2n/(2n-1)}} $$ where $\delta>0$ is small and $n$ is large. For $n=2$ and $\delta=1/10$ it looks like this:
alt text http://www.math.hawaii.edu/%7Ebjoern/Teaching/MO.jpg
Bjørn Kjos-Hanssen
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