Consider the sequence $ (x_n)_{n\ge 0}$ where $ x_n\equal{}2^{n}\minus{}1\ ,\ n\in \mathbb{N}$. Determine all the natural numbers $ p$ for which:

\[ s_p\equal{}x_0\plus{}x_1\plus{}x_2\plus{}...\plus{}x_p\]

is a power with natural exponent of $ 2$.