# How do you find the radius of convergence #Sigma (1*4*7* * * (3n+1))/(n!)x^n# from #n=[0,oo)#?

##### 1 Answer

Jan 17, 2017

The radius of convergence is

#### Explanation:

The ratio test states that a necessary condition for

if

We then evaluate the ratio for the series at hand:

so that:

The series is then absolutely convergent for