Tetrahedron recursion, building a cake

I know this will sound silly. But I'm building a parametric cake for my nephew and I need to test it first in GH. The idea is to create a series of Tetrahedrons on each vertice of it I'll place a sphere (chocolate sphere). I need to know how many spheres will I need. But i need to create a definition that allows me to repeat the number of tetrahedrons exponentially. Hope its clear enough.

any ideas, refere to the images for visual explanation an GH definition

thank you