The pentominoes are the 12 ways to pick 5 squares from a square lattice. In general, picking connected objects from a lattice is a polyform. This Demonstration shows 12 different lattices that can be used for polyforms, with four varieties given for each type. Included are the polyominoes, polyhexes, polyiamonds, polytans, polydrafters, polyrhombs, polyrects, polykites, polypons, polycairos, polyedges, and triangular polyedges.
Andrew Clarke, "The Poly Pages," http://www.recmath.com/PolyPages/.
Peter Esser, "Peter's Puzzle and Polyform Pages," http://mitglied.lycos.de/polyforms/.
Bob Harris, "Bob's Puzzle Pages," http://www.bumblebeagle.org/.
Wolfram Demonstrations Project
Published: May 19 2009