Was there an Apollo 3?
Not really, although Apollo 2 had some near misses with naming, Apollo 3 never really came about. AS-203 was in fact the 3rd Apollo flight (But flew before the second flight, oddly) and was nearly named Apollo 3 after the Apollo 1 fire, but the name never stuck. So the result was, there never was an Apollo 3.
15 named missions made up the Apollo Project. Not including Skylab and Apollo-Soyuz