A# 13/F#
The A# 13 chord consists of the A# (Perfect unison), D (Major third), F (Perfect fifth), G# (Minor seventh), C (Major ninth) and G (Major thirteenth) notes, with F# as the bass note.

How to play the A# 13/F# chord
- Play F# as the lowest bass note in the left hand
- Find A# (Root) on the piano keyboard
- Add D (Major third) — 4 semitones above A#
- Add F (Perfect fifth) — 7 semitones above A#
- Add G# (Minor seventh) — 10 semitones above A#
- Add C (Major ninth) — 14 semitones above A#
- Add G (Major thirteenth) — 21 semitones above A#
- Press all 7 notes simultaneously to sound the A# 13/F# chord