Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & ContributorsRepeated Addition and Doublinghttp://demonstrations.wolfram.com/RepeatedAdditionAndDoubling/]]>http://demonstrations.wolfram.com/RepeatedAdditionAndDoubling/Two-Dimensional Neighbor-Dependent Substitution Systemshttp://demonstrations.wolfram.com/TwoDimensionalNeighborDependentSubstitutionSystems/]]>http://demonstrations.wolfram.com/TwoDimensionalNeighborDependentSubstitutionSystems/