Which formula can be used to find the nth term of a geometric sequence where the fifth term is 1/16 and the common ratio is 1/4?

Any geometric sequence can be expressed as:

a(n)=ar^(n-1), a=initial term, r=common ratio, n=term number

We are given that a(5)=1/16 and r=1/4 so we can say:

1/16=a(1/4)^(5-1)

1/16=a(1/4)^4

1/16=a/256

256/16=a

16=a

So the initial term is 16 so our formula is:

a(n)=16(1/4)^(n-1)