Fry's Geometric Demonstration of the Sum of Cubes
The sum of the first cubes is given by the remarkable identity[more]
Fry [1, 2] gave a geometrical proof of this result based on the slicing of cubes into square slabs and their assembly into a square. For an even summand, one of the square slabs is cut in half for each end of the L-shape.[less]
 A. L. Fry, "Proof without Words: Sum of Cubes," Mathematics Magazine, 58(1), 1985 p. 11. doi:10.2307/2690228.
 D. Treeby, "Applying Archimedes's Method to Alternating Sums of Powers," The Mathematical Intelligencer, 40(4), 2018 pp. 65–70. doi:10.1007/s00283-018-9821-7.