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 4-[(7-amino-6-bromo-3-quinolin-3-ylpyrazolo[1,5-a]pyrimidin-5-yl)methyl]piperazin-2-one is given. What is its corresponding molecular formula?
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C20H18BrN7O
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