Answer:
If my theory is right the next 3 numbers are 21,28,36
Explanation:
Looking at the beginning you see that 3 goes to 6 which is a hop of 3
Then next is 6 to 10 which is a hop of 4
Then next is 10 to 15 which is a hop of 5
So I think it’s going in a chronological number order
So I say the next hops will be 6,7,8