PermPy is a python library for the manipulation of permutations and permutation classes. It is useful for experimentation and forming conjectures, and has played a role in about a dozen publications in the field of permutation patterns.
The GuessFunc algorithm takes as input known initial terms of a combinatorial sequence and attempts to guess a generating function that is either rational, algebraic, D-finite, or D-algebraic. It can apply a number of transformations to guess OGFs, EGFs, reciprocals, reversions, and more.
The method of differential approximants approximates the asymptotic behavior of a combinatorial sequence based on a finite number of known initial terms. It has been used by statistical mechanists for decades. This is the first open-source publicly available implementation.