The future with οὐ interrogative is used in questions in an imperative sense to express urgency, warning, or irony: οὐκ ἔξιμεν . . . οὐκ ἐπὶ τὴν ἐκείνου πλευσόμεθα; shall we not go forth . . . shall we not set sail against his country?
a. μή with the future in a prohibitive sense is used in a few suspected passages (
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].