A028792 Nonsquares mod 79.

3, 6, 7, 12, 14, 15, 17, 24, 27, 28, 29, 30, 33, 34, 35, 37, 39, 41, 43, 47, 48, 53, 54, 56, 57, 58, 59, 60, 61, 63, 66, 68, 69, 70, 71, 74, 75, 77, 78

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• fini
• full
• easy

Examples

			x^2 = 7 mod 79 has no solutions, hence 7 is in the sequence.
x^2 = 8 mod 79 has the solutions x = 18 and x = 61, so 8 is not in the sequence.
		

Crossrefs

Cf. A010440 (complement), A096013 (row 79).

Programs

Magma

[n: n in [0..78] | not IsSquare(R! n) where R:= ResidueClassRing(79)]; // Vincenzo Librandi, Jan 23 2020

Mathematica

Complement[Range[78], PowerMod[Range[78], 2, 79]] (* Alonso del Arte, Jan 15 2017 *)

PARI

isok(n) = (n < 79) && (kronecker(n, 79) == -1); \\ Michel Marcus, Jan 15 2017

PARI

isok(n) = (n < 79) && (! issquare(Mod(n, 79))); \\ Michel Marcus, Jan 15 2017

Scala

(0 to 78).diff((1 to 79).map(n => n * n % 79)) // Alonso del Arte, Jan 22 2020

Formula

Legendre symbol (a(n)/79) = -1. - Alonso del Arte, Jan 15 2017