You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named (1R,2S,3S,5S,8S,9R,11R,16S,17R)-3,9,16,17-tetrahydroxy-12,12-dimethyl-6-methylidenepentacyclo[7.6.1.15,8.01,11.02,8]heptadecane-7,10-dione is given. What is its corresponding molecular formula?
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C20H26O6
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