If P= [(√ 3)/2, 1/2; -1/2, (√ 3)/2], A= [1, 1; 0, 1] and Q = PAP^T, then P^T Q^2015 P is:

If $\displaystyle P=\left[\begin{array}{cc}\frac{\sqrt{3}}{2} & \frac{1}{2} \\ -\frac{1}{2} & \frac{\sqrt{3}}{2}\end{array}\right], A=\left[\begin{array}{cc}1 & 1 \\ 0 & 1\end{array}\right]$ and $\displaystyle \mathrm{Q}=\mathrm{PAP}^{\mathrm{T}}$, then $\displaystyle \mathrm{P}^{\mathrm{T}} \mathrm{Q}^{2015} \mathrm{P}$ is :