A Locrian scale
The A Locrian scale has the formula 1, b2, b3, 4, #4, b6, b7 with notes A, A#, C, D, D#, F, G
The Locrian scale is the seventh of the seven modes. Of the modes, it is the most minor sounding. The tonic chord is diminished, which makes it less suitable for most popular music, but it is still sometimes used in jazz.