Which of these sequences is an arithmetic sequence?
1,2,4,8,…1, 2, 4, 8, \dots1,2,4,8,…
1,4,9,16,…1, 4, 9, 16, \dots1,4,9,16,…
2,5,8,11,…2, 5, 8, 11, \dots2,5,8,11,…
1,−1,1,−1,…1, -1, 1, -1, \dots1,−1,1,−1,…