Originally Posted by

**Greg98** Hmm. There's one problem with your formula. For $\displaystyle 2 \times 2$ it gives $\displaystyle 4$. But I think there's only $\displaystyle 2$ of those $\displaystyle 2 \times 2$ matrices. All $\displaystyle 2 \times 2$ matrices:

0. $\displaystyle \left(\begin{array}{cc}0&0\\0&0\end{array}\right)$

1. $\displaystyle \left(\begin{array}{cc}0&0\\0&1\end{array}\right)$

2. $\displaystyle \left(\begin{array}{cc}0&0\\1&0\end{array}\right)$

3. $\displaystyle \left(\begin{array}{cc}0&0\\1&1\end{array}\right)$

4. $\displaystyle \left(\begin{array}{cc}0&1\\0&0\end{array}\right)$

5. $\displaystyle \left(\begin{array}{cc}0&1\\0&1\end{array}\right)$

6. $\displaystyle \left(\begin{array}{cc}0&1\\1&0\end{array}\right)$

7. $\displaystyle \left(\begin{array}{cc}0&1\\1&1\end{array}\right)$

8. $\displaystyle \left(\begin{array}{cc}1&0\\0&0\end{array}\right)$

9. $\displaystyle \left(\begin{array}{cc}1&0\\0&1\end{array}\right)$

10. $\displaystyle \left(\begin{array}{cc}1&0\\1&0\end{array}\right)$

11. $\displaystyle \left(\begin{array}{cc}1&0\\1&1\end{array}\right)$

12. $\displaystyle \left(\begin{array}{cc}1&1\\0&0\end{array}\right)$

13. $\displaystyle \left(\begin{array}{cc}1&1\\0&1\end{array}\right)$

14. $\displaystyle \left(\begin{array}{cc}1&1\\1&0\end{array}\right)$

15. $\displaystyle \left(\begin{array}{cc}1&1\\1&1\end{array}\right)$

Only 0. and 15. qualify, I think. So, we need new equation or I'm completely lost. Thanks.