C thirteenth chord
C13 chord for piano presented by keyboard diagrams.
Explanation: The C thirteenth is a seven note chord. Due to practical circumstances, some notes (as a suggestion fifth, ninth, and eleventh) is omitted and the chord is played inverted. The chord is often abbreviated as C13.
Theory: The C thirteenth chord is constructed by adding a third to an eleventh chord.
Notes: C - E - G - Bb - D - F - A