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. 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 T'ien's experiences with his loyal roommate and his friends, and a surprising relationship that he develops with the local "Playboy".
This film was banned in Singapore because it "portrayed homosexuality as normal, and a natural progression of society".
Naïve country bumpkin Chou T'ien Tsai goes to Taipei to meet an internet friend face-to-face. Being a romantic, and believing in 'true love' (he even has a book called Love Is A Kind Of Faith), he is sorely disappointed when his internet friend, Kevin, suggests they have sex with no love. T'ien instead goes to a bar and runs into his ex-classmate Yu and Yu's friend CC. In the same bar, he encounters the 'Number One Playboy' Bai Tieh Nan, who is notorious for one night stands. Despite professing his dislike for 'men who play with love', T'ien can't help but be drawn to Bai.
T'ien becomes roommates with Yu. Yu enlists another friend, Alan, to try and set T'ien up with someone so he'll lose his virginity, but their efforts fail against T'ien's unyielding belief in saving himself for true love. T'ien later gets a job as a clubhouse attendant, where he has several run-ins with Bai, who seems to like T'ien mutually. Despite warnings from his friends and rumors about Bai's past, T'ien very quickly develops a liking towards Bai.
Scenes with Bai and his psychologist show that Bai has a problem kissing people despite having no qualms about sleeping with them. After being advised to practice kissing a mirror and then a mannequin, both of which fail to help him, he tries to kiss his longtime friend, Jun, but can't bring himself to do it.
One night, T'ien shows up at Bai's doorstep and they end up kissing and having sex consensually. True to his nature, Bai disappears the next day, leaving Jun to turn up at his house and explain to T'ien that 'he hopes you don't misunderstand', causing T'ien to misunderstand the situation. T'ien, hurt and unknowing of the entire story behind Bai's intimacy issues, leaves a message saying that 'this kind of misunderstanding won't happen again'.
Later, Bai, who would like to make amends with T'ien, is thwarted from doing so before having to leave for an important business trip.
After failing to reach Bai by phone, T'ien prepares to leave his roommate's dwelling and return to his own home. Meanwhile, T'ien's friends corner Bai and Jun as they get back from the business trip. They ask Bai to tell them the truth, but Bai is very resistant to tell the story, so Jun decides to share instead. As a young boy, Bai was told by a fortune teller that he is cursed and that anything that he loves will be doomed. A lifetime of self-fulfilling this prophecy is what led Bai to become a serial one-night stander and lose his ability to love. Falling in love with T'ien caught Bai off guard and, as a result, they both suffered. After a silent prayer for a second chance, he sees T'ien heading up an escalator. His first attempt to apologize fails, and T'ien literally runs away. He nearly gets run down by a scooter, but Bai saves him and they make up.
The ending credits include a short segment on Yu, CC, and Alan and their somewhat stereotyped views upon gay fashion.Tony Yang as Chou T'ien Tsai
Duncan Lai as Bai Tieh Nan/Richard Bai
King Chin as Yu
Jason Chang as Jun
Dada Ji as C.C.
James Yun as Alan
Jeff Locker as Ray
Ladder Yu as Kevin
Huang Guan-Jie as Jay
Yang Tze-Long as the plumber
The film was the highest grossing fiction film in Taiwan in 2004.