Sierpiński's triangle (itself a two-dimensional analogue of the Cantor Set) has been generalized to the tetrix (Fig. 5), pyramid (Fig. 6), carpet (Fig. 7), and sponge (Fig. 8) […]
2007, Bruce M. Landman, Melvyn B. Nathanson, Jaroslav Nesetril, Combinatorial Number Theory: Proceedings of the 'Integers Conference 2005' in Celebration of the 70th Birthday of Ronald Graham, Carrollton, Georgia, USA, October 27-30, 2005, page 213