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What is the molecular formula of the compound with this IUPAC name methyl (2S,3R,5R)-4,4-dimethyl-12-oxotetracyclo[11.4.0.02,5.06,11]heptadeca-1(17),6,8,10,13,15-hexaene-3-carboxylate ?
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C21H20O3
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