These notes are natural harmonics.

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--12------------------------------|
------9------7--------------------|
--------9------7------------------|
----------9-----------------------|
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The rest of the song is the following (the baseline is also the same thing)
Repeat it until you get tired, then go back to the harmonics.
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2-2-2-8-8-8-7-7-7-4-4-4-5-5-4-5---|
0-0-0-6-6-6-5-5-5-2-2-2-3-3-2-3---|