Each cell holds a binomial coefficient, built only by adding the two cells above it. Cells are shaded by their remainder after dividing by m. With m = 2, the empties line up and the Sierpinski gasket steps out of plain arithmetic — nobody drew it, it was hiding in the sums. Slide m to 3, 4, 5 and watch the fractal mutate into its cousins. Drag the Rows slider to 64 and the cells shrink so the whole gasket fits your screen at once. Hover or tap any cell to see its pedigree. Press Go 3D for the sequel: Pascal's Pyramid, where every cell is the sum of three parents, and the same rule builds the gasket's true three-dimensional heir, the Sierpinski tetrahedron. Drag to spin it, scroll or pinch to zoom.