Answer:
If n is divisible by 4, then the answer is 1;
If n-1 is divisible by 4, then the answer is i;
If n is divisible by 2, but not by 4, then the answer is -1;
If n-1 is divisible by 2, but not by 4, then the answer is -i.
Step-by-step explanation:
Hope that helps.