Press 'S' to draw the next iteration.
1x'S' = 4 pyramids, 16 triangles.
2x'S' = 16 pyramids, 64 triangles.
3x'S' = 64 pyramids, 256 triangles.
4x'S' = 256 pyramids, 1024 triangles.
Mouse to rotate.
Added filler-request by @raucket
How many times can you press S? My computer can only make it to 4 before the program is so slow that the entire tetrahedron cannot be filled in one frame (the whole thing is rendered so slowly that for a little bit it only shows you part of it.