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-(2,3,4,4a,5,6,7,7a-octahydropyrrolo[3,4-b]pyridin-1-yl)-2-(3-bromophenyl)ethanone by IUPAC nomenclature, provide its molecular formula.
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C15H19BrN2O
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