Mathematica provides direct access to a large volume of mathematical data, specially organized and created for Mathematica. The data is available in a wide range of forms suitable for direct integration into Mathematica computations.
FiniteGroupData — properties of named finite groups
GraphData — properties of named and enumerated graphs
KnotData — properties of enumerated knots
LatticeData — properties of named lattices
PolyhedronData — geometry and properties of polyhedra
FindSequenceFunction — find functional forms for integer sequences
ExampleData — example and test-case data