In a geometric sequence, each term is found by multiplying the previous term by a common ratio. The sequence you provided is defined recursively as follows:
- \(a_1 = 56\)
- \(a_n = 4a_{n-1}\)
From this definition, we can see that to get from one term to the next, we multiply by 4.
Thus, the common ratio \(r\) is:
\[ r = 4 \]
So, the answer is 4.