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For the molecule named 1-[(10R,13R)-13-fluoro-3,10-dimethyl-2,3,4,7,8,9,11,12,14,15-decahydro-1H-cyclopenta[a]phenanthren-17-yl]benzimidazole by IUPAC nomenclature, provide its molecular formula.
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C26H31FN2
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