11. The integer b _ 2 = 15 is also Very Smooth Quadratic Residue modulo n. 12. Every finite field of this type has exactly quadratic residues and exactly quadratic non-residues. 13. But it is known that there are distinct quadratic residues ( mod ) ( besides 0 ). 14. Is a root of unity if and only if \ chi is the quadratic residue symbol modulo p. 15. In other words, 5 is a quadratic residue modulo p iff p is a quadratic residue modulo 5. 16. In other words, 5 is a quadratic residue modulo p iff p is a quadratic residue modulo 5. 17. But 2 is not a quadratic residue modulo 5, so it can't be one modulo 15. 18. These are the nonzero codewords of the quadratic residue code of length 7 over the field of 2 elements. 19. He became a research student of John Edensor Littlewood, working on the question of the distribution of quadratic residues . 20. This may be expressed by saying that " 1 is a quadratic residue mod " p ".
