The first harmonics of the note A4, with the frequency of 440 Hz, are 880 Hz, 1320 Hz, and 1760 Hz. These numbers correspond to the first four integer multiples of the fundamental frequency. Among them, you can identify the notes:
A4, A5, and A6 (respectively, the first, second, and fourth multiples); and
E5, which together with A5 creates a perfect fifth.
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