So. I thought " well I 'm gonna just look at the  what actual digit strings do occur in the training data. "
Right.
And the interesting thing was it turns out that there are no sequences of two - long or three - long digit strings  in any of the Aurora training data. So it 's either one , four , five , six , uh up to eleven , and then it skips and then there 's some at sixteen.
But what about the testing data ?