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 (6a-hydroxy-9a-methyl-3-methylidene-2,9-dioxo-4,5,6,7,8,9b-hexahydro-3aH-azuleno[4,5-b]furan-6-yl)methyl 2-methylbut-2-enoate is given. What is its corresponding molecular formula?
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C20H26O6
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