A aug/C#
The A aug chord consists of the A (Perfect unison), C# (Major third) and F (Minor sixth) notes, with C# as the bass note.

How to play the A aug/C# chord
- Play C# as the lowest bass note in the left hand
- Find A (Root) on the piano keyboard
- Add C# (Major third) — 4 semitones above A
- Add F (Minor sixth) — 8 semitones above A
- Press all 4 notes simultaneously to sound the A aug/C# chord