self ref function and its generating function

Question

Let $h_0 =1 $ and $ h_n = h_{n-1} + \sum \limits_{j=0}^{n-1} h_j h_{n-1-j}$ for $n\geq 1$,

And i am asked to find closed form for $H(x) = \sum h_n x^n$ ?

With a recurrence of finite number of previous terms I now know how to do it, but this is new to me!

Thanks in advance.