A Geometric Proof of the Square Pyramidal Number Formula


	The pyramidal numbers 1, 5, 14, 30, … are the sums of the square numbers, . This Demonstration shows a geometric proof of the square pyramidal number formula, . In the figure the six pyramids of side length form an cuboid.


	Contributed by: Okay Arik

Square Pyramidal Number (Wolfram MathWorld)

"A Geometric Proof of the Square Pyramidal Number Formula" from The Wolfram Demonstrations Project
http://demonstrations.wolfram.com/AGeometricProofOfTheSquarePyramidalNumberFormula/

Contributed by: Okay Arik

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3D Graphics
Number Theory
Recreational Mathematics

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