(I don't want to accuse you of sexism; I'm personally no doubt sexist, for being raised in a culture where traditional gender identity is very important. And I hope the original poster didn't say anything that could be construed as "propoganda we're going to hear form you Lisp people.")
Historically, there's many aspects of mathematics. Proof-based mathematics isn't the only form. Davis and Hersh
argued: "The mathematics of Egypt, of Babylon, and of the ancient Orient was all of the algorithmic type. Dialectical mathematics -- strictly logical, deductive mathematics -- originated with the Greeks. But it did not displace the algorithmic." And the physicist Feynman argued
that, "In physics, we need the Babylonian method, and not the Euclidian or Greek method."
That said, there's some attributes of Lisp that might be of use when you're playing with math. So for example, mathematicians (and anyone else) have fluid notations. Well, Lisp's notation is handy in this respect -- it's fairly abstract and you can manipulate it with the same data-handling muscles you've already trained. Not to mention that you can play with the reader, for character-level syntax. (Other programming languages usually offer less moldable notations, for good or bad.)
Not to mention that Common Lisp has relatively nice support for numbers. So you're not too worried about integer overflow, and you have rationals and complex numbers...
There's proof systems in Lisp, though I'm not familiar with them. My vague impression is that computers are still currently more help aiding a human proof-discoverer, then discovering the proofs themselves.
About the riddle, a pizza is not a mathematical object; it is something for which a horizontal cut is usually difficult to perform, which is why it was viewed from a 2D perspective. Not to mention a geometry where there's no weird curvature or something, even though pizzas can of course be curved, leading to more (and simpler to carry out) solutions. But it's a cool riddle, if you phrase it carefully enough, which you did. (So for example, you didn't refer to a pizza "slice," but rather "parts." I assumed you were being as informal with your language as you were with spelling, which was no doubt a mistake on my part.)
(Ironically, in his essay, Feynman discussed the exasperation that physicist has when mathematicians talk of many dimensions, when the physicist just wants the special case of 3... until it turns out that maybe 4 was interesting too. Maybe I'm currently stuck in Babylon, too?)
Lest we look down on those practicing the Babylonian style, I've heard the argument (from Connes, Gowers, Smolin or someone; can't remember) that physicists have often been responsible for trailblazing mathematical fields due in part to their greater willingness to be very loose and intuitive with their mathematical reasoning, as compared to mathematicians.