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system
Provide the molecular formula for the IUPAC named substance 2-methyl-6-[[(4R)-2,3,4,5-tetrahydro-1-benzoxepin-4-yl]methyl]-5,7-dihydro-3H-pyrrolo[3,4-d]pyrimidin-4-one .
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C18H21N3O2
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