You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (19S)-10,19-diethyl-7,19-dihydroxy-3,13,17-triazapentacyclo[11.8.0.02,11.04,9.015,20]henicosa-1(21),2,4(9),5,7,10,15(20)-heptaene-14,18-dione by IUPAC nomenclature, provide its molecular formula.
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C22H21N3O4
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