PGF of Discrete Random Variable

Hi Everyone,

I am trying to show that the discrete random variable....

P(R=j) = , j = 0,1,2,.... 0<p<1

Has a P.G.F.....

GR(s) = ( )^2

Above is meant to be the whole fraction to the power 2, but i was having some Latex Syntax problems showing that (Thinking)

I have tried changing and to and taking it outside the summation when beginning to try and find the PGF but i didnt get anywhere, help needed please! (Nod)

Also maybe = 1 for any a where a < 1 can be used? i cant see how though!