Music is, at its very core, mathematical. Harmonics are ratios; rich sounds are produced as a result of the interplay of fundamental frequencies and partials. Some, like Tom Johnson and Seth Horvitz, have been far more explicit in their use of mathematics as composition. While searching for something else on The On-line Encyclopedia of Integer Sequences, I was incredibly pleased to find the linked page, which generates a MIDI file from any of the OEIS’s sequences. Handful of curated sequences on the front page, but even beyond that it’s all great fun.