You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 11-ethyl-5-methoxy-8-methyl-8,16-diazapentacyclo[10.6.1.01,9.02,7.016,19]nonadeca-2(7),3,5,13-tetraen-10-ol by IUPAC nomenclature, provide its molecular formula.
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C21H28N2O2
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