Some nice examples from "The Encyclopedia of Integer Sequences". These examples were obtained using the Combstruct package, which is included in the standard distribution of Maple V.4.

Gaļa: a package for the random generation of combinatorial structures by Paul Zimmermann. Published in the Maple Technical Newsletter vol. 1 nb. 1 (9 pages, 300 Kbytes)

Reference for the theoretical model : A Calculus for the Random Generation of Labelled Combinatorial Structures by Philippe Flajolet, Paul Zimmermann and Bernard Van Cutsem, Theoretical Computer Science, volume 132, numbers 1-2, pages 1-35, 1994.

Random generation of the powerset construction

the Maple implementation of Gaļa for Maple V Release 3