You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-methyl-4-(2-phenylethoxy)-1-(7H-purin-6-yl)-5,7-dihydro-4H-pyrazolo[3,4-b]pyridin-6-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H19N7O2
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