This answer to Did Apollo 13 produce any scientific results? begins:
In addition to crashing the Saturn V's S-IVB into the moon to collect seismic data from sensors installed by the crews of Apollo 11 and 12...
How many times were artificially induced seismic events intentionally performed (i.e. things "crashed into the Moon for science")? These could be artificial objects that hit the lunar surface with the primary intention of making seismic signals, or things that were going to hit anyway but had their trajectory optimized or at least monitored in some way in hopes of contributing some information to the seismic analysis.