I have a problem, I need to calculate the Fourier coefficients of a function, which I do not have the value, but rather have some points in a graph. I need to calculate the coefficients of the frequency that appears the most (440Hz, which is the fundamental frequency) and a frequency that does not appear at all (Like for example 1550Hz). I would like to know how can I get to which value of $n$ I should use on the formula.
Thank you for your help!