Answer:
256, 1024, 4096
Explanation:
Divide the last two numbers by each other, you get 4, basic math skills state 1x4 is 4 then multiply 4 x 4 and you get 16. this shows that each number is mulpiplied by 4, to keep the sequance going multiple 64 by 4 then the product by 4 and so on.