17/13
17/13 |0 0 0 0 0 -1 1>
464.4277 cents
In 17-limit Just Intonation, 17/13 is the "septendecimal sub-fourth," measuring about 464.4¢. It is the mediant between 13/10 and 4/3 and falls in the categorically-ambiguous zone between supermajor third and perfect fourth that Margo Schulter calls interseptimal. It appears in the harmonic series between the 13th and 17th harmonics.
It is less than .2 cents flat of 31edo's subfourth of 464.52c (12\31).