You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named tert-butyl N-[(1S)-1'-(5-bromo-3H-imidazo[4,5-b]pyrazin-2-yl)spiro[1,3-dihydroindene-2,4'-piperidine]-1-yl]carbamate by IUPAC nomenclature, provide its molecular formula.
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C23H27BrN6O2
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