You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule [(2R,3S)-5-[2-amino-6-(methylamino)purin-9-yl]-3-hydroxy-4-methyl-2,3-dihydrofuran-2-yl]methyl 2-cyclohexylacetate into molecular formula.
user
C20H28N6O4
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