Back to the $$1\leftarrow2$$machine with 4 boxes.

The machine:

• The dots initially go into the right most box.
• Whenever there are two (or more) dots are in the same box, then two dots will explode and become one dot on box to the left, unless there is no box one place to the left.

You put in 16 dots (in the right most box). In the final display, what is the number of dots in these boxes?

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