Question: Which country participated in the Eurovision Song contest in 1957 but absent in 1970 and submitted the song co-written by Sebastian F. Ovens?
Sentence (from "Australia in the Eurovision Song Contest 2015"): In 2015 for example, the Australian coloratura soprano of Armenian descent Mary-Jean O'Doherty participated in the Eurovision Song Contest 2015 contest as part of the group Genealogy representing Armenia.
Relevant evidence: No