In this simplified case I showed above, a(1) is 3 This is sometimes called the explicit formula, because you can generate any term if you know the first value and multiplier (common ratio). If you don't adjust the exponent by one, you will find terms that are in the wrong location. You can write a quick, general formula from this for all geometric sequences:įirst value x multiplier raised to number of the term, minus one If you have an original number of 3, your term numbers i would look like this top row.

Another way to think of it is that every time you need a new term, you multiply by 2.