Consider an A.P.: \( a_{1}, a_{2}, \ldots , a_{n} ;\ a_{1}, > 0 \). If \( a_{2} - a_{1} = -\dfrac{3}{4} \), \( a_{n} = \dfrac{1}{4} a_{1} \), and \( \displaystyle \sum_{i=1}^{n} a_{i} = \dfrac{525}{2} \), then \( \displaystyle \sum_{i=1}^{17} a_{i} \) is equal to:
