You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (1R,3S,6R,7R,8S,9S,10S,11R,12R,13S,16S,17R)-8-tert-butyl-6,9,12,17-tetrahydroxy-16-methyl-2,4,14,19-tetraoxahexacyclo[8.7.2.01,11.03,7.07,11.013,17]nonadecane-5,15,18-trione by IUPAC nomenclature, provide its molecular formula.
user
C20H24O11
assistant