You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 1-[(E)-2,5-dihydroxy-3-methylpent-3-enyl]-2,5,5,8a-tetramethyl-3,4,4a,6,7,8-hexahydro-1H-naphthalene-2,6-diol by IUPAC nomenclature, provide its molecular formula.
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C20H36O4
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