You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (3S,3aR,7S,8aR)-3,7-dimethyl-6-[(3R)-3-[(2S,3S,4R,5S,6S)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxybutyl]-3,3a,4,7,8,8a-hexahydrocyclohepta[b]furan-2-one by IUPAC nomenclature, provide its molecular formula.
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C21H34O8
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