The Pythagorean augmented 2nd, 19683/16384, may be reached by stacking 9 3/2's and octave reducing. It differs from the classic minor third, 6/5, by the schisma, and, as a result, the Pythagorean augmented second is in fact rather consonant. According to Aura, while 19683/16384 may take the place of the classic minor third in chords, its status as a augmented second means that it has a different function in terms of voice-leading. If it is tempered out, you set the fifth to 5/9 and divide the octave into 9 parts, although only 9edo does this in it's patent val. If it is used as a generator, it produces Hanson.