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For the molecule named 3-[[7,7-dimethyl-2-(2-methylbut-3-en-2-yl)-1H-pyrano[2,3-g]indol-3-yl]methyl]-1-methoxy-7,8-dihydro-6H-pyrrolo[1,2-a]pyrazin-4-one by IUPAC nomenclature, provide its molecular formula.
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C27H31N3O3
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