Petrmic triad

The petrmic triad is a 13-limit essentially tempered dyadic chord consisting of two 13/10 intervals followed by a 13/11, in other words a 13/10-13/10-13/11 chord, tempered by the petrma, 2200/2197, so that it closes at the octave. Another way to say this is that it is the petrmic tempering of 1-13/10-22/13 or 1-13/11-20/13. Equal temperaments with petrmic triads include 29, 37, 50, 53, 58, 84, 87, 111, 121, 140, 190, 198, 224, 311, 414, 422, and 612. 37, 50 and especially 29 have notably good petrmic triads.