One problem I've been having some trouble with is finding an expression for $\displaystyle A^n$ where $\displaystyle A=\left(\begin{array}{cc}1&4\\2&3\end{array}\right )$

I've found a similar problem on Wikibooks/Wikipedia, but those aren't the best examples. I just need someone to explain a streamlined process of how to solve one of these (using the concepts of diagonalizability). Any help?