I created a scale from I-IV-V

[wju425]

Playing around with I-IV-V I realized where the blue notes may have come from. This is from the modulation method and not the inversion. Let's play with C

I - C D E F G A B C
IV - F G A Bb C D E F
V - G A B C D E F# G

Bb and F# not found on ( I ) so I added them converting F# to Gb

C D E F Gb G A Bb B C

I came up with this scale

I II III IV bV V VI bVII VII

Looks like a blues scale to me.