You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 1'-[(4-chloro-1-methylindazol-3-yl)methyl]spiro[1,2-dihydroindole-3,4'-piperidine] is given. What is its corresponding molecular formula?
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C21H23ClN4
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