how to write a recursive formula?

n is the POSITION OF THE N'TH TERM.

IN THE SEQUENCE   3,5,7,9,11,.....

The second term is 5

the 5th term is 11

the n'th  term could be written as 2n+1

In this context n cannot be 0.  What is the 0th term?  It does not make sense!

The formula would be.......

(-1)ⁿ * 8^(n-1)      (where n ≥ 1)

Hi, I was looking at this today in my work but doesnt n equal to the nth term, with values (in most cases 0,1,2,3,4,5,6,7...; but which could be set to be less than 1 also I guess.) Is this right, could you elaborate for me please. Thanks.

Recursively:  The first term is -1.

Each term after the first is found by taking the previous term times -8.

Thus, the recursive formula:  t(1) = -1

                                           t(n) = -8 · t(n-1)

Thanks Gino,  I don't remember hearing that wording before.  Thank you.