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'''Legendre's three-square theorem''' states that any [[natural number]] that is not of the form <math>4^a(8b + 7)</math> for integers a and b can be represented as the sum of three integer squares
'''Legendre's three-square theorem''' states that any [[natural number]] that is not of the form <math>p = 4^a(8b + 7)</math> for integers ''a'' and ''b'' can be represented as the sum of three integer squares:


:<math>p = x^2 + y^2 + z^2\ </math>
:<math>p = x^2 + y^2 + z^2\ </math>


This theorem was stated by [[Adrien-Marie Legendre]] in 1798.<ref>Conway. Universal Quadratic Forms and the Fifteen Theorem. [http://www.fen.bilkent.edu.tr/~franz/mat/15.pdf]</ref> His proof was incomplete, leaving a gap which was later filled by [[Carl Friedrich Gauss]].
This theorem was stated by [[Adrien-Marie Legendre]] in 1798.<ref>Conway. Universal Quadratic Forms and the Fifteen Theorem. [http://www.fen.bilkent.edu.tr/~franz/mat/15.pdf]</ref> His proof was incomplete, leaving a gap which was later filled by [[Carl Friedrich Gauss]].<ref>{{cite journal |last1=Dietmann |first1=Rainer |first2=Christian |last2=Elsholtz |title=Sums of two squares and one biquadrate |journal=Funct. Approx. Comment. Math |volume=38 |number=2 |year=2008 |pages=233-234}}</ref>


== Notes ==
== Notes ==
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[[Category:Additive number theory]]
[[Category:Additive number theory]]
[[Category:Theorems in number theory]]
[[Category:Theorems in number theory]]



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Revision as of 15:15, 6 October 2013

Legendre's three-square theorem states that any natural number that is not of the form for integers a and b can be represented as the sum of three integer squares:

This theorem was stated by Adrien-Marie Legendre in 1798.[1] His proof was incomplete, leaving a gap which was later filled by Carl Friedrich Gauss.[2]

Notes

  1. ^ Conway. Universal Quadratic Forms and the Fifteen Theorem. [1]
  2. ^ Dietmann, Rainer; Elsholtz, Christian (2008). "Sums of two squares and one biquadrate". Funct. Approx. Comment. Math. 38 (2): 233–234.

See also