You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (2R)-N-[(2S)-1-[(3aR,6S,6aS)-6-acetamido-3,3a,4,5,6,6a-hexahydro-2H-cyclopenta[b]pyrrol-1-yl]-3,3-dimethylbutan-2-yl]-2-methylbutanamide by IUPAC nomenclature, provide its molecular formula.
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C20H37N3O2
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