three lines between notes

Those notes are tremolo between notes. In the palette there are two sets of tremolos. One has a stem, one does not. This is the one that does not. Use notes that are half the duration they look like, in this case quarter notes, and apply the tremolo to the first note. The appearance of the notes will change to look like your picture.

One clue that this must be tremolo is that the math will never work for the notes to not be tremolo.