I am finding the radius of convergence and interval of convergence.

the sum of n=1 to infinity of x^n/(6^n*n^4)

i used the ratio test on this and found that the limit goes to 1 and the radius of convergence is 6.

when x is -6, i know the series alternates but when i compare b of n to b of n+1 I don't see how b of n is greater than b of n+1 which is one of the stipulations for the alternating series test.