Epogdoon

With Epogdoon the ratio 9 is referred to 8, so the Ganztonintervall in the Pythagorean tuning in music theory. For example, are the natural numbers 18 and 16 in this relation.

According to Plutarch, the Pythagoreans hated the number 17 because it separates the 16 from their Epogdoon. Next they called the 17 "barrier", especially because Osiris said to have died on the 17th.