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 8-hydroxy-9-(hydroxymethyl)-3,6-dimethylidene-4,5,6a,7,8,9,9a,9b-octahydro-3aH-azuleno[4,5-b]furan-2-one is given. What is its corresponding molecular formula?
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C15H20O4
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