The equation is y''-4xy'-4y= e^x, assuming that y=(sigma from 0 to infinity) c_nx^n, a=0

So I did the substitution and found the recurrence term to be

c_n+2 = [(8nc_n)/(n+2)(n+1)]

I just have to find the first six terms of the solution but how do I get the first two terms? (since when n=0 I get c_2)