You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[6-[(3,5-dimethyl-1,2-oxazol-4-yl)methyl]-5,7-dihydro-4H-thieno[2,3-c]pyridin-3-yl]-(4-ethylpiperazin-1-yl)methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H28N4O2S
assistant