Data.Combinatorics.Factorial:
    * Various implementations
    * Get direct access to the GMP version.
    * Benchmarking

Data.Combinatorics.Binomial:
    * Other implementations?

* Memory analysis. E.g., making sure we can replicate Luschny's memory bound for binomials.

* Talk to people re integrating HaskellForMaths, gamma, statistics, erf, math-functions, combinat, species, multiset-comb,...