You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 1,3-diethyl-8-[(E)-2-[3-fluoro-4-(oxetan-3-yloxy)phenyl]ethenyl]-2H-purine is given. What is its corresponding molecular formula?
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C20H23FN4O2
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