Question

8,-8,8,-8 in explicit formula

Answer 1

If i=a counter=1, n=8.
If i= 2, n=-8.
If i= 3, n=8
and so on...
You need to develop a formula for this, so that if I give you an 'i' value, you can tell me what the corresponding value of n will be.

Answer 2

for i = 1, 2, 3, ...
(-1)^i = -1, 1, -1, ...