Article date: Dec 1974
Article title: The arts as combinatorial mathematics, or how to compose like Mozart with dice
Mathematical Games column? Y
Book: 12. Time Travel and Other Mathematical Bewilderments
Chapter: 7. Melody-Making Machines
This data confirmed? yes
Notes
Peter Rowlett (27 August 2022):
Peter Rowlett initial guess (Uncertain)
Peter Rowlett (2 September 2022):
I have seen copies of Scientific American Dec 1974 and Melody-Making Machines in Time Travel and Other Mathematical Bewilderments and these match.