For each of the following sequence, find a reasonable formula for an that matches the given terms: 1 1 1 1 1. {n}_1= -. - 3'5'7 9.} -8-16 2. {a} {-3, 2, - 3'9' 27} 3. {an} = {1,0,−1,0,1,0,−1,0,...} (Hint: Think about a trigonometric function.)