What are the three missing numbers in 271217?

In the sequence 271217, the missing numbers can be determined by analyzing the pattern of the numbers. By looking at the sequence closely, we can see that the missing numbers are 18, 19, and 20. This is because the sequence follows a pattern of increasing by 1 from the previous number. Therefore, the missing numbers after 17 would be 18, 19, and 20 to complete the sequence.