c_n=\left\{\begin{array}{cl}
0, & \textrm{ ako je } \ n \equiv 1,3(\mod 4)\\
 (-1)^{\frac{n-2}{4}+1} \frac{\cos 1}{(\frac{n-2}{2}+1)!}, & \textrm{ ako je} \ n \equiv 2(\mod 4) \\
(-1)^{\frac{n}{4}} \frac{\sin 1}{(\frac{n}{2})!}, & \textrm{ ako je }\ n \equiv 0(\mod 4)
\end{array}\right.