2.1.5 The Legendre and Jacobi symbols
The Legendre symbol is a useful tool for keeping track of whether or not an integer a
is a quadratic residure modulo a prime p. Further background and pro ofs of the facts
presented here can be found in references given in [10, 12, 13].
Definition 2.1.16 Let p be an odd prime and a an integer. The Legendre Symbol (a/p) is defined to be
