For this case we have the following sequence:
0.8
3.2
12.8
51.2
This sequence can be written as:
0.8 = 0.2 * 4 = 0.2 * 4 ^ 1
3.2 = 0.2 * 16 = 0.2 * 4 ^ 2
12.8 = 0.2 * 64 = 0.2 * 4 ^ 3
51.2 = 0.2 * 256 = 0.2 * 4 ^ 4
Therefore, we have that the generic expression for this case is:
an = 0.2 * 4 ^ n
Then, the next number is then:
a5 = 0.2 * 4 ^ 5 = 0.2 * 1024 = 204.8
answer
the next number in the pattern is 204.8