Formula 17 (17歲的天空, pinyin: shí qī suì de tiān kōng) is a 2004 film which was directed by Chen Yin-jung (陳映蓉). It stars Tony Yang (楊佑寧), Duncan (周群達), King Chin (金勤), Dada Ji (季宏全), Jimmy Yang (楊俊明), and Jason Chang (張大鏞). It is a gay romantic comedy film about Chou T'ien-Tsai, a romantic Taiwanese male who takes a trip to visit an online boyfriend in person for the first time.