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Number Theory Linear Algebra Polynomial Equation

Number theory

Jacobi symbol

Let a is an integer and n an odd number. Let that the n is equal to p1n1p2n2...pknk The Jacobi symbol denoted by (a/n) is defined as
(a/n)=(a/p1)n1(a/p2)n2 ... (a/pk)nk
where (a/pi) is the Legendre symbol (i=1,2,...,k).

If (a/n)=-1 then a is not quadratic residual modn.
If (a/n)=1 we cannot conclude.

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