Formula 17 (Chinese: 17歲的天空; pinyin: Shíqī Suì de Tiānkōng) is a 2004 Taiwanese film directed by Chen Yinjung. It stars Tony Yang, Duncan Chow, King Chin, Dada Ji, Jimmy Yang, and Jason Chang. It is a gay romantic comedy film about Chou Tien Tsai, a romantic Taiwanese young man who takes a trip to visit an online boyfriend in person for the first time. Finding his internet relationship unsuitable for his real life, he moves on with his life and rooms with an old time friend of his. The film describes Tien's experiences with his loyal roommate and his friends, and a surprising relationship that he develops with the local "Playboy".