A Mixolydian

A1B2C♯3D4E5F♯6G♭7

Major with a flattened seventh: the scale that fits a dominant seventh chord without altering it.

Written out

Fig. 2 · A Mixolydian, ascending

Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.

AWBWC♯HDWEWF♯HGWA

A Mixolydian is A, B, C♯, D, E, F♯ and G, and back to A.

Its steps are W – W – H – W – W – H – W, where W is a whole step and H a half.

On the same tonic, A major differs from it by exactly one note.

Across the first twelve frets of the ukulele its notes fall in 31 places, which is what makes a scale a shape rather than a list.

Found by testing every chord in the catalogue against these 7 sounds, not chosen.