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What is the molecular formula of the molecule identified by (1R,4S,7R,17S)-7-hydroxy-3',6,7-trimethylspiro[2,9-dioxa-14-azatricyclo[9.5.1.014,17]heptadec-11-ene-4,2'-oxirane]-3,8-dione ?
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C18H25NO6
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