There is a machine with $m (2\leq m\leq 30)$ coloured bulbs and a button.When the button is pushed, the rightmost bulb changes.
For any changed bulb,
if it is red now it will be green;
if it is green now it will be blue;
if it is blue now it will be red and the bulb that on the left(if it exists) will change too.
Initally all the bulbs are red. What colour are the bulbs after the button be
pushed $n (1\leq n< {2}^{63})$ times?