While we're talking about mathematical music theory it is very nice to see @vihart on here of whom I have been a huge fan for many years...

Any interest in microtonality? Was just talking to @keenanpepper about how the Riemann zeta function can be thought of as measuring the harmonicity of an equal temperament. Maybe of interest to you? https://en.xen.wiki/w/The_Riemann_zeta_function_and_tuning