Safe to use a 16 amp motor on a 20 amp circuit with a 15 amp outlet?
Just change out the receptacle

I bet your tablesaw has a 5-20 plug on it, which won't fit into a 5-15 receptacle. Since you have a 20A circuit, though, there's nothing wrong with having a 5-20T duplex receptacle on it, or even changing all the receptacles on the circuit to 5-20Ts from 5-15s.  This shouldn't be too tricky a job, as long as you turn off the breaker before you start (of course), change the receptacles one at a time, and note down how things were wired before you start unhooking them.  Also, if the existing receptacle is a 15A GFCI, it'll need to be replaced with a 20A GFCI, not a regular receptacle.