Geometric sequence is a sequence in which each term after the first term a is obtained by multiplying the previous term by a constant r, called the common ratio. It is obvious that a ≠ 0 and r ≠ 0 or 1.
1, 2, 4, 8, 16, 32, . . . is a geometric sequence.
Each term of this geometric sequence is multiplied by the common ratio 2.