A Geometrical Way to Sum Powers by Means of Tetrahedrons and Eulerian Numbers
arXiv:1103.4288
Abstract
We geometrically prove that in a d-dimensional cube with edges of length n, the number of particular d-dimensional tetrahedrons are given by Eulerian numbers. These tetrahedrons tassellate the cube, In this way the sum of the cubes are the sums of the tetrahedrons, whose calculation is trivial.
12 pages, based on lecture notes to undergraduaded students