C# m3/A#
The C# m3 chord consists of the C# (Perfect unison) and E (Minor third) notes, with A# as the bass note.

How to play the C# m3/A# chord
- Play A# as the lowest bass note in the left hand
- Find C# (Root) on the piano keyboard
- Add E (Minor third) — 3 semitones above C#
- Press all 3 notes simultaneously to sound the C# m3/A# chord