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What is the molecular formula of the compound with this IUPAC name 2-amino-9-[(1S,6S,8R,10R,17R,18R)-9,18-difluoro-8-(6-oxo-1H-purin-9-yl)-3,13-bis(sulfanyl)-2,4,7,12,14,16-hexaoxa-3-phosphatricyclo[13.2.1.06,10]octadecan-17-yl]-1H-purin-6-one ?
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C21H22F2N9O8PS2
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