For example in my textbook it says that the sequence for the generating function
$$f(x) = (2x-3)^3$$
is
$$-27,54,-36,8,0,0,0,\dots$$
I can see that plugging $0$ into the function gives me $-27$, but this doesn't hold true for $1$ and $54$. How do I get this sequence or the correct sequence for another generating function like
$$f(x) = \frac{x^3}{1-x^2}\;?$$