Chord sequence
C7 F7 C7 F7 C7 G7 F7 C7 D♭7
In every key
Four-note rootless voicings in their two forms, with the 3rd or the 7th on the bottom, played over the root.
Heard in C major
Over C7 · V7/IV
Mode 5 of Major
Over F7 · IV7
Mode 4 of Melodic Minor
Over C7 · I7
Over G7 · V7
Over Db7 · subV7