Answer:
In the sequence the previous number is always added again, for example in the first 3 + 3 = 6 and then the sequence is 12, only 6 + 6 = 12 is added, then 24 + 24 = 48 is also added. Then 48 + 48 = 96
So, the sequence would look like this:
3,6,12,24,48,96
I hope this help you :)
