21/13
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| Ratio | 21/13 |
| Factorization | 3 × 7 × 13-1 |
| Monzo | [0 1 0 1 0 -1⟩ |
| Size in cents | 830.25325¢ |
| Name | tridecimal supraminor sixth |
| Color name | thuzo 6th, 3uz6 |
| FJS name | [math]\text{M6}^{7}_{13}[/math] |
| Special properties | reduced |
| Tenney height (log2 nd) | 8.09276 |
| Weil height (log2 max(n, d)) | 8.78463 |
| Wilson height (sopfr(nd)) | 23 |
| Harmonic entropy (Shannon, [math]\sqrt{nd}[/math]) |
~4.2186 bits |
[sound info] | |
| open this interval in xen-calc | |
21/13, the tridecimal supraminor sixth, is ca. 830 cents in size. It has a very good approximation in 13edo.
This interval is a ratio of two consecutive Fibonacci numbers, therefore it approximates the golden ratio, specifically acoustic phi. In this case, 21/13 is ~2.8 ¢ flat of the golden ratio.