You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4S,4aR,5R,8aS)-2,2-dimethyl-4-(4-trimethylsilylbut-3-ynyl)spiro[4,4a,6,7,8,8a-hexahydrobenzo[d][1,3]dioxine-5,2'-cyclopentane]-1'-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H34O3Si
assistant