This is off-topic but since so many mathematicians love music I thought some of you might be able to provide useful leads: Is there anything like an Online Encyclopedia of Chord Progressions and/or a forum for "recreational musicology"? Of course, trying to list occurrences of IV - V - I in Western music would be as impossible as listing occurrences of 1,3,5,7,9,... in the mathematical literature, but less common chord progressions might be trackable. For instance, if you listen to the "Blazing Saddles" theme ( https://m.youtube.com/watch?v=hzRmp-O496Y ; 00:41-00:42 and elsewhere) and the "Big Country" theme (https://m.youtube.com/watch?v=AQTH3a0mjR8 ; 00:04-00:05 and 00:44-00:45 and elsewhere) you'll hear an C-major chord going to an A-major chord with a suspended E in the melody (before the song goes back to the D major tonic). How did VII-flat - V - I become a cowboy movie cliche? Does it trace back to actual cowboy music, or is it purely a Hollywood creation? And what are the antecedents in classical music? There may be a fun story here, but how would one search the internet to find it? Jim Propp