To finish my work, I need to obtain the general term of the power series of the below function:
$$\frac{1}{\cos{x}-\cos{b}}$$
where $b$ is any real number. Transcendent functions are welcome, I know it will be impossible to have a formula for this without a transcendent function. Btw, I want this formula to be valid always (infinite radius of convergence).
Thanks in advance.