Prove-or-disprove-cos-1-1-3-1-2-cos-1-1-3-2pi-2-2-cos-1-1-3-3pi-3-2-0-

Question Number 137637 by Dwaipayan Shikari last updated on 04/Apr/21

Prove or disprove

\frac{c o s (1 + \frac{1}{\sqrt{3}}) π}{1^{2}} + \frac{c o s (1 + \frac{1}{\sqrt{3}}) 2 π}{2^{2}} + \frac{c o s (1 + \frac{1}{\sqrt{3}}) 3 π}{3^{2}} + \dots = 0