Can use 17 resistors with 16 rgb led's?
If you only have one LED on at a time, that should work, but it's going to be difficult to have Green and Blue visible at the same time.  The slightly lower forward voltage will take nearly all the current, and you won't see the other one.  Not so sure about Red and something else, because of the extra resistor.

The general rule is that you can't share resistors across multiple LED's that are supposed to be on at the same time and expect anything close to the same brightness.