[mrob]

Both square and triangle waves contain only odd harmonics, with the high harmonics of the triangle wave rolling off faster. The sawtooth wave contains both odd and even harmonics. You can't have a wave with pure even harmonics because the fundamental is counted as an odd harmonic. If you half-wave rectify a sine wave you get only even harmonics above the fundamental, but to my ears this just sounds like two separate tones: the sine fundamental and a separate higher pitched odd-harmonic wave.