ISO module for binomial coefficients, etc.

[kj]

Before I go off to re-invent a thoroughly invented wheel, I thought
I'd ask around for some existing module for computing binomial
coefficient, hypergeometric coefficients, and other factorial-based
combinatorial indices.  I'm looking for something that can handle
fairly large factorials (on the order of 10000!), using floating-point
approximations as needed, and is smart about optimizations,
memoizations, etc.

TIA!

~K