A major sharp eleventh (lydian) piano chord - Amaj9#11
The A major sharp eleventh (lydian) chord is a 6-note chord consisting of the notes A, C#, E, G#, B and D#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Amaj9#11.
Interactive piano diagram for the A major sharp eleventh (lydian) chord
Chords that are a subset of Amaj9#11. These contain less notes but all of them are included in Amaj9#11.