Power Series Interval of Convergence

[harrietstowe]

Homework Statement

I need a power series with a radius = pi. (So when you do the ratio test on this power series you get pi)

Homework Equations

The Attempt at a Solution

I tried x^n*sin(n) and thought of stuff like that but couldn't come up with a working power series

 

[ystael]

Look at the ratio or root test and try to figure out how to change the radius of convergence of a power series, so that you can start with a power series whose radius of convergence you know, and turn it into one that solves your problem.