"Regular tetrahedra whose vertices have integer coordinates" by Eugen J. Ionascu
 

Document Type

Article

Publication Date

2011

Publication Title

Acta Math. Univ. Comenianae

Abstract

In this paper we introduce theoretical arguments for constructing a procedure that allows one to find the number of all regular tetrahedra that have coordinates in the set {0, 1, ..., n}. The terms of this sequence are twice the values of the sequence A103158 in the Online Encyclopedia of Integer Sequences [16]. These results lead to the consideration of an infinite graph having fractal nature which is tightly connected to the set of orthogonal 3-by-3 matrices with rational coefficients. The vertices of this graph are the primitive integer solutions of the Diophantine equation a 2 + b 2 + c 2 = 3d 2 . Our aim here is to lay down the basis of finding good estimates, if not exact formulae, for the sequence A103158.

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Mathematics Commons

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