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2013 | OriginalPaper | Buchkapitel

On Representation of an Integer by X 2 + Y 2 + Z 2 and the Modular Equations of Degree 3 and 5

verfasst von : Alexander Berkovich

Erschienen in: Quadratic and Higher Degree Forms

Verlag: Springer New York

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Abstract

I discuss a variety of results involving s(n), the number of representations of n as a sum of three squares. One of my objectives is to reveal numerous interesting connections between the properties of this function and certain modular equations of degree 3 and 5. In particular, I show that
$$\displaystyle{ s(25n) = \left (6 -\left (-n\vert 5\right)\right)s(n) - 5s\left (\frac{n} {25}\right) }$$
follows easily from the well known Ramanujan modular equation of degree 5. Moreover, I establish new relations between s(n) and h(n), g(n), the number of representations of n by the ternary quadratic forms
$$\displaystyle{2{x}^{2} + 2{y}^{2} + 2{z}^{2} - yz + zx + xy,\quad {x}^{2} + {y}^{2} + 3{z}^{2} + xy,}$$
respectively. Finally, I propose a remarkable new identity for s(p 2 n)−p s(n) with p being an odd prime. This identity makes nontrivial use of the ternary quadratic forms with discriminants p 2, 16p 2.

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Metadaten
Titel
On Representation of an Integer by X 2 + Y 2 + Z 2 and the Modular Equations of Degree 3 and 5
verfasst von
Alexander Berkovich
Copyright-Jahr
2013
Verlag
Springer New York
DOI
https://doi.org/10.1007/978-1-4614-7488-3_2

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