You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 9,19-dioxa-1,11-diazatetracyclo[9.9.2.03,8.013,18]docosa-3(8),6,13,15,17-pentaen-10-one by IUPAC nomenclature, provide its molecular formula.
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C18H20N2O3
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