If we consider $(\mathbb{Z}/2\mathbb{Z})^2$ (n=2) as a vector space, we get the Bases:
B1 = {$\begin{pmatrix}1\\0\end{pmatrix},\begin{pmatrix}0\\1\end{pmatrix}$} B2 = {$\begin{pmatrix}1\\0\end{pmatrix},\begin{pmatrix}1\\1\end{pmatrix}$} B3 = {$\begin{pmatrix}0\\1\end{pmatrix},\begin{pmatrix}1\\1\end{pmatrix}$}
So we get 3 Bases
For n=3 I came up with the following calculation: $${7*6*4\over 3!}= 28$$ There are $2^3$ possible vectors in $(\mathbb{Z}/2\mathbb{Z})^3$ and the Bases must have 3 linearly independent vectors.
A Basis does not include the $0$ vector so 7*(number of possible vectors left (6))*(number of vectors left that aren't a linear combination of the first two (4)) and we divide that by 3! since we don't care about the order in which the vectors are chosen.
So we get 28 Bases
My questions are: Is this correct so far? and does $$\prod_{k=0}^{n-1}{(2^n-2^k)\over (k+1)}$$
work as a possible general formula for any n? (I don't know how to show this)
It would be much appreciated if you could help me show this a little bit more rigorously.