Bong.mp3 

1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
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Fn = Fn - 1 + Fn - 2
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3 + 2 = 5
5 + 3 = 8
8 + 5 = 13
13 + 8 = 21
21 + 13 = 34
34 + 21 = 55
55 + 34 = 89