You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 7-tert-butyl-2-methyl-3,4,4a,5,6,7,8,8a-octahydro-2H-benzo[b][1,4]thiazine 1-oxide by IUPAC nomenclature, provide its molecular formula.
user
C13H25NOS
assistant