第一个等式： $\frac{2^2-1^2-1^2}{2}$=1，第二个等式： $\frac{3^2-2^2-1^2}{2}$=2，第三个等式： $\frac{4^2-3^2-1^2}{2}$=3…

请用上述等式反映出的规律解决下列问题：

    What's On?

    Electric Underground

    7.30p.m. —1.00a.m.        Free at the Cyclops Theatre

    Do you know who's playing in your area? We're bringing you an evening of live rock and pop music from the best local bands. Are you interested in becoming a musician and getting a recording contract (合同)? If so, come early to the talk at 7.30pm by Jules Skye, a successful record producer. He's going to talk about how you can find the right person to produce you music.

    Gee Whizz

    8.30p.m.—10.30p.m.        Comedy at Kaleidoscope

    Come and see Gee Whizz perform. He's the funniest stand-up comedian on the comedy scene. This joyful show will please everyone, from the youngest to the oldest. Gee Whizz really knows how to make you laugh! Our bar is open from 7.00pm for drinks and snacks (快餐).

    Simon's Workshop

    5.00p.m.—7.30p.m.        Wednesdays at Victoria Stage

    This is a good chance for anyone who wants to learn how to do comedy. The workshop looks at every kind of comedy, and practices many different ways of making people laugh. Simon is a comedian and actor who has 10 years' experience of teaching comedy. His workshops are exciting and fun. An evening with Simon will give you the confidence to be funny.

    Charlotte Stone

    8.00p.m.—11.00p.m.        Pizza World

    Fine food with beautiful jazz music; this is a great evening out. Charlotte Stone will perform songs from her new best-selling CD, with James Pickering on the piano. The menu is Italian, with excellent meat and fresh fish, pizzas and pasta (面食). Book early to get a table. Our bar is open all day, and serves cocktails, coffee, beer, and white wine.