You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(2E)-2-[(3aS,5aR,9aR,9bS)-3a,6,6,9a-tetramethyl-1,4,5,5a,7,8,9,9b-octahydrobenzo[e][1]benzofuran-2-ylidene]-3,4-dioxobutyl] acetate is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H32O5
assistant