I have a Loop station (Phrase recorder) and I began be recording a 3 chord, chord progression (A Major, D Major, E Major) over and over. Then I was just trying to find a scale to go with it. I started playing different notes until I got it. The scale is (D, E, F#, G#, A, B, C#, D). Without having to just experiment and just hit notes at random, how do I know how to find that scale?

Thanks in advance!!!