Hi Angelina, this is a good question! Note in fact that this question is different than question 6.7 that we did in class. This is due to the fact that in this recursive definition we take $a_{n+1}$ mod 11 as part of the sequence definition. For example, the first few terms of the sequence are $$2, 5, 1, 4, \ldots$$(Just to be very clear here, these are the actual terms of the sequence, so $a_2 = 5$.) Therefore we can try to find a pattern like we do for many remainder problems. Hope this helps!