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-[5-(4-chlorophenyl)-7-methyl-5,8-dihydrotetrazolo[1,5-a]pyridin-6-yl]-2-(1H-indazol-5-yl)ethanone is given. What is its corresponding molecular formula?
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C21H17ClN6O
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