find the limits : $\lim_{n}( \frac{1\cdot3\cdot5\cdot \cdot \cdot(2n-1)}{2\cdot4\cdot6 \cdot \cdot \cdot (2n)} ) =?$
To show for following sequence $\lim_{n \to \infty} a_n = 0$ where $a_n$ = $1.3.5 ... (2n-1)\over 2.4.6...(2n)$