Question 6
The first five terms of a sequence are shown.
$$1,2,1,-1,-2,\ldots$$
After the second term, each term can be obtained by subtracting from the previous term the term before that. What is the sum of the first 42 terms of this sequence?
$$1,2,1,-1,-2,\ldots$$
After the second term, each term can be obtained by subtracting from the previous term the term before that. What is the sum of the first 42 terms of this sequence?