Answer
See below.
Work Step by Step
According to the exercise $a_1=3072$ and $a_n=0.25 a_{n-1}$. The rule makes sense if $a_n$ is an integer.
Hence here $a_1=3072,a_2=768,a_3=192,a_4=48,a_5=12,a_6=3$
After that $a_n$ will not be an integer, thus the rule makes sense for $n=1,2,3,4,5,6$
