* Photo: Sian Kennedy * In the new Futurama DVD Bender's Big Score, the characters encounter Al Gore driving a taxi — a hybrid taxi, naturally. Some viewers may chuckle when they notice that the license plate on the former Vice President's cab reads NOCO2. But very few will realize that the the badge number on another cab, 87539319, is also a joke.

Math geeks, however, will find that number hilarious because of something that happened about a century ago. The British mathematician G.H. Hardy was paying a call on the Indian mathematician Srinivisa Ramanujan. "I had ridden in taxi cab number 1729 and remarked that the number seemed to me rather a dull one," Hardy later recalled. Ramanujan disagreed. "It is a very interesting number," he insisted. "It is the smallest number expressible as the sum of two cubes in two different ways."

The number 1729 can be expressed as 13 + 123 or it can be expressed as 93 + 103. The number 87539319 can be expressed as the sum of two cubes in three different ways, as 1673 + 4363 or as 2283 + 4233, or 2553 + 4143. Much scholarly research has since been dedicated to so-called taxicab numbers like these. Which means that a tiny percentage of mathematically inclined Futurama viewers will get a chuckle when they see a cartoon taxi that has a taxicab number printed on it.

Futurama, a show made by geeks for geeks, is shot through with impossibly obscure references like that. "The number on Al Gore's cab in that scene also has a secret meaning," says David X. Cohen, who codeveloped Futurama with Matt Groening and serves as showrunner. Cohen refuses to reveal the other gag, but if you visit a fan site like GotFuturama.com a few days after the DVD goes on sale, you're likely to find a screenshot and a detailed explanation written by one of the hardcore fans. "If you care enough, you frame-advance through it," says Cohen. "They've earned that moment of pleasure."

Cohen takes his math very seriously. In his office at Matt Groening's studio, he shows me a 25-year-old plaque commemorating a math team victory. He placed third in the entire state of New Jersey, and his team from Dwight Morrow High School in Englewood took first place in the state during his senior year, irking the preppies they competed against. "It killed them that they were beaten by public school kids," he chuckles.

"As a general rule, I hate watching TV or movies with mathematicians in it," Cohen says. "It never rings true. They're portrayed as magic beings. There's an implication that a normal person can't do math because they don't have this magic power, which is very discouraging. You don't have to have Math-Ray Vision." Cohen is wearing a Math-Club T-shirt. Unlike the plaque, this shirt isn't a cherished memento from his childhood. It's from an actual club for grownup math fans in the LA area.

Courtesy of Twentieth Century Fox Film CorporationCohen was a physics major at Harvard, and he went on to study theoretical computer science at UC Berkeley, earning a master's. He decided to pursue comedy writing instead of academia, but his wonkiness often worked its way into his scripts. In a 1995 Simpsons episode, Cohen devised an equation that appears briefly behind Homer Simpson:

178212 + 184112 = 192212

The equation appears to be a counterexample to a famous mathematical statement, Fermat's Last Theorem. Pierre de Fermat had proposed the theorem in 1637, and a proof had only recently been discovered when the episode aired. Cohen wrote a computer program to find near-misses for Fermat's Last Theorem, equations that were close enough to being true that a person who tapped it into a calculator would be fooled. The willingness to put that much effort into a gag that only a small fraction of his audience could possibly get would serve him well a few years later on Futurama. (Download the original C program here.)

As showrunner on Futurama, Cohen assembled a team of writers with equally wonky backgrounds. Ken Keeler, who scripted the pilot as well as the new DVD, has a PhD in applied math. Stewart Burns, who wrote the Emmy-winning episode "Roswell That Ends Well," has a master's in math. There are also PhDs in chemistry, philosophy, and computer science. "It was the nerdiest writers' room I'd ever been in, and that's saying something," says Eric Horsted, whose previous experience on sitcoms like Home Improvement and Coach didn't prepare him for the intense discussions about string theory and quantum mechanics.

Futurama was geek-friendly to begin with: Episodes are built around sci-fi staples like parallel universes, spaceship battles, and time travel. But look more closely and you'll spot fleeting jokes that are geekier than a Slashdot comments thread, gags about the Heisenberg Uncertainty Principle, particle physics, and the P=NP problem.

This sort of material helped make Futurama a cult favorite that fans wanted to buy on DVD and frame-advance through, looking for more hidden treasure. The show was canceled in 2002, but its popularity on DVD and in syndication led Fox to green-light four feature-length DVDs worth of new shows. One of the bonus features on the first of the new DVDs explores the role of math on the show. "The lecture is by professor Sarah Greenwald of Appalachian State University," says Cohen. "She discusses various mathematical references over the history of the series, and her talk is intercut with clips from the episodes she refers to." (Greenwald has a raft of interviews with the Futurama writers online here.)

Cohen refers to a One Percent Rule that guided the writing on Futurama. When they were scripting the episode "Kif Gets Knocked Up a Notch," a character claims that he painstakingly programmed a holographic simulation using "4 million lines of BASIC." One writer pointed out that 99 percent of the audience wouldn't get the reference to an old programming language. Producer-writer Eric Kaplan responded, "Fuck them!"

As long as it doesn't derail the enjoyment of the 99 percent, Futurama will make a joke tailored to the nerdiest 1 percent of its audience. "That 1 percent becomes a fan for life," says Cohen.

FEATURE Futurama Is Back! Grab a Can of Slurm and

Settle In