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Interval information
Ratio 20/9
Factorization 22 × 3-2 × 5
Monzo [2 -2 1
Size in cents 1382.4037¢
Name Ptolemaic ninth
Color name y9, yo 9th
FJS name [math]\text{M9}^{5}[/math]
Tenney height (log2 nd) 7.49185
Weil height (log2 max(n, d)) 8.64386
Wilson height (sopfr (nd)) 15
Harmonic entropy
(Shannon, [math]\sqrt{n\cdot d}[/math])
~4.55211 bits
open this interval in xen-calc

20/9, the Ptolemaic ninth; the ratio between the 20th and 9th harmonics; one octave above 10/9.