You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (6S,8S)-6-hydroxy-8-(4-methoxyphenyl)-5-methyltricyclo[6.5.0.02,7]tridec-4-en-3-one by IUPAC nomenclature, provide its molecular formula.
user
C21H26O3
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