You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (9R)-10-[(1S)-1-cyclopropylethyl]-1,13-dimethyl-10-azatricyclo[7.3.1.02,7]trideca-2(7),3,5-triene-4-carboxamide by IUPAC nomenclature, provide its molecular formula.
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C20H28N2O
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