nostr:npub1knzsux7p6lzwzdedp3m8c3c92z0swzc0xyy5glvse58txj5e9ztqpac73p 
There's a tuning system that includes 7 as well as 2, 3, and 5.
https://en.wikipedia.org/wiki/31_equal_temperament#:~:text=In%20music%2C%2031%20equal%20temperament,steps%20(equal%20frequency%20ratios).