25/16, the classic(al) augmented fifth or diptolemaic augmented fifth is the interval obtained by stacking two 5/4 major thirds, however, it gains additional isoharmonic identity from its position between 11/8 and 7/4, so it can frequently be used in conjunction with those, even in chords.

Interval information
Ratio 25/16
Factorization 2-4 × 52
Monzo [-4 0 2
Size in cents 772.6274¢
Names classic(al) augmented fifth,
diptolemaic augmented fifth
Color name yy5, yoyo 5th
FJS name [math]\displaystyle{ \text{A5}^{5,5} }[/math]
Special properties reduced,
reduced harmonic
Tenney norm (log2 nd) 8.64386
Weil norm (log2 max(n, d)) 9.28771
Wilson norm (sopfr(nd)) 18

[sound info]
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See also