Gregorian leap week

Gregorian leap week is a rank 2 temperament produced by temperament-merging 71edo and 400edo with the purpose of creating a scale that mimics the distribution of years with 53 weeks.

400edo supports the GregorianLeapWeek[71] scale with 231\400 as the generator, which is close to 5/12 syntonic comma meantone. In the 19-limit, the generator corresponds to 525/352 and the comma basis is 969/968, 1001/1000, 2128/2125, 3328/3325, 4225/4224, and 444528/444125.

An interesting variation upon the scale is the ISOWeek[71], which contains all the years which have 53 weeks in the current calendar system. It is a maximum variety 3 scale, with step sizes of mostly 5, 6, and once 7. Unlike the smoothly spread scale which has 231\400 in the Irvian mode, the ISOWeek[71] has 232\400 fifth, which corresponds to the 696-cent fifth of 50edo.