In nusach Ashkenaz, the chazzan's repetition of Shmona Esrei skips the paragraph beginning with "אתה קדוש ושמך קדוש", and connects the qedusha with the following brakha ("אתה חונן לאדם דעת") by means of a paragraph that commences, "לדור ודור נגיד גדלך".
I am given to understand (but have no source) that if the congregation is pressed for time, the chazzan can skip the repetition by starting the Shmona Esrei out loud, continuing until qedusha, reciting qedusha and then letting everybody daven the rest of Shmona Esrei silently, to themselves. In the event that this happens, should he say "לדור ודור", or let them all say "אתה קדוש"?