Using thirds is a real cool trick. A great producer one told me in a session, "why play one note, when you can play two!!" :) and these are a great way of doing just that without making it too busy... almost like using little chords.
This is an A7 lick, uses the A Mixolydian Mode which are the same notes as the D Major Scale (D E F# G A B C# D). If you are not sure about modes yet, then I have a lesson on The Mixolydian Mode, or just be cool with playing the shapes, I didn't understand the theory for many years after I learned this type of lick.
Being a modal kind of lick, this lick works over an A7 NOT an A Blues, you have to change the licks as the chords change!