You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(10aR)-4,4a,5,6,6a,6b,7,8,10a,11,11a,11b-dodecahydro-3H-benzo[a]carbazole is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H23N
assistant