I assume that by sequence they mean $\displaystyle {\alpha\choose 1}$$\displaystyle +{\alpha\choose 2}+...+{\alpha\choose n}$

I do not understand what should be $\displaystyle n$... Is it complex? Usual binomial coefficients have both $\displaystyle n $ and $\displaystyle \alpha$ integers and $\displaystyle n\leq\alpha$. In this problem can $\displaystyle n$ be more than $\displaystyle \alpha$??