piano chord
A♯13
A♯1C𝄪3E♯5G♯♭7B♯9F𝄪13
Seven notes in theory and four or five in anyone’s hands: root, third, seventh and thirteenth carry it.
Written the other way round it is B♭13 — the same twelve keys on a piano, a different piece of notation.
What is true of it
A♯13 is A♯, C𝄪, E♯, G♯, B♯ and F𝄪 — 1, 3, 5, b7, 9 and 13 counted from A♯.
C𝄪 and F𝄪 are double sharps, and they have to be: every letter from A♯ upwards is used once, so the 3 cannot be written any other way.
On an instrument that cannot reach all 6, the 5, 9 and 1 go first, in that order.