Here is a sequence of numbers:
1, 2, 4, 8, 16, 32, 64, 128...
Starting at 1, we get the next number by multiplying by 2 or doubling the previous number.
These numbers are also called the powers of 2.
20 = 1
21 = 2
22 = 4
23 = 8
24 = 16
25 = 32
26 = 64
27 = 128
... etc...
The 'powers of 2' are an example of a geometric sequence, where each term after the first is found by multiplying the previous term by a fixed number, called the common ratio. The common ratio is 2.
The 'powers of 2' sequence goes on for ever. It is infinite and grows quickly!