The 5-note tones in Close Encounters took a long time to get down. Composer John Williams partnered with Spielberg to come up with the distinct musical method of communication between the humans and aliens a year before filming. Williams wanted a 7-note sequence, but it was too drawn out for Spielberg who wanted a simple greeting. So the composer hired a mathemetician to calculate how many 5-note combos they could make from a 12-note scale. The answer was larger than 134,000. Williams whittled it down to 100 different combinations, and they worked it down from there.