C sharp/ D flat major piano scale. From the Root note C sharp, we create the C sharp piano major chord. Then using the piano formula for major scales- RWWHWWWH (R for root note, W for whole step and H for half step), we create our C sharp major scale.
From the above diagram, piano notes C#, F and G# when struck together creates the C# major piano chord. Then applying the piano major scales formula, we get the following notes depicted in the below diagram: C#,D#,F, F#, G#, A#, C,and C# again. This is what is termed as C# piano major scale.
Note that the C sharp major scale notes are the same as the same as the D flat major scales notes, with the notes: Db, Eb, F, Gb, Ab, Bb, C and Db. Also the D flat major piano chord is the same as the C sharp major chord with the notes Db, F and Ab.