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-[(3,4-dichlorophenyl)methyl]-3,7-dimethyl-8-[2-(methylamino)ethylamino]-6-methylidenepurin-2-one by IUPAC nomenclature, provide its molecular formula.
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C18H22Cl2N6O
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