Indetermination in a complex fourier series I determined the complex Fourier series of a sinusoidal signal and arrived at the following expression:
$$\sum_{n=\infty}^{\infty} \left[\frac{4e^{-j \frac{\pi}{2}n}}{\pi(1-n^2)}(e^{-j\pi n}+1)\right]e^{-j \frac{\pi}{2}tn} $$
However, we have a division by zero at $n = 1$ and $n = -1 $. Is there any way to determine $D_{-1}$ and $D_1$?
HINT:
You need to go back to the original definition of the Fourier coefficients via the integral, and treat $|n|=1$ as a special case. Your mistake happened there already (you divided by zero).