What is the molecular formula of the molecule (2E)-3-butyl-2-[(2E,4E)-5-(3-butyl-1,1-dimethyl-3a,4,5,9b-tetrahydrobenzo[e]indol-3-ium-2-yl)penta-2,4-dienylidene]-1,1-dimethyl-3a,4,5,9b-tetrahydrobenzo[e]indole ?