You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 1-[(3aS,8aR)-2,3,3a,4,5,7,8,8a-octahydro-1H-pyrrolo[3,4-d]azepin-6-yl]-2-(2-bromo-4-nitrophenyl)ethanone;hydrochloride by IUPAC nomenclature, provide its molecular formula.
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C16H21BrClN3O3
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