I've solved this now, no need for a response, but if anyone ever comes across a similar problem here is the solution:
Take x_{n}=(1, \frac{1}{\sqrt{2}}, \frac{1}{\sqrt{3}}, ..., \frac{1}{\sqrt{n}}, 0, 0, 0 ,0,...)
Obviously, as a series with a finite number of non-zero terms, it is square...