If you want to go above 13 overtones or make other waveforms, I quickly whipped this up for square/triangle/sawtooth/impulse trains: https://www.desmos.com/cal

If you want to go above 13 overtones or make other waveforms, I quickly whipped this up for square/triangle/sawtooth/impulse trains: https://www.desmos.com/calculator/eioaj93rzr https://www.desmos.com/calculator/eioaj93rzr