Finding sequences on the TI-89 Titanium Calculator?

[jonathan1]

Can someone guide me toward using my TI-89 Titanium calculator for sequences?

I would like to be able to PUT IN a sequence of numbers and have it GIVE ME the formula. Not vice versa please. Thanks.

 

[sjb-2812]

I would suggest there must be some limit to this - there are probably infinite answers to "guess the next term".

For instance, what do you think is the next term for 1, 2, 4, 8, 16?

 

[jonathan1]

What I mean is that I'd like to put in a sequence of numbers such as (1, -1/3, 1/9, -1/27, 1/81,...) and have it give me a formula like (-1/3)^n-1

 

[sjb-2812]

So you want a simplest formula, for some values of simplest? I am not sure of an easy way to do this, except perhaps look for things like common ratios / differences, perhaps taken over several steps?