A028743 Nonsquares mod 30.

2, 3, 5, 7, 8, 11, 12, 13, 14, 17, 18, 20, 22, 23, 26, 27, 28, 29

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• fini
• full

Examples

			Since 5 is not a perfect square and there are no solutions to x^2 = 5 mod 30, 5 is in the sequence.
Although 6 is not a perfect square either, there are solutions to x^2 = 6 mod 30, such as x = 6, x = 24, so 6 is not in the sequence.
		

Crossrefs

Cf. A010462.

Programs

Mathematica

Complement[Range[30], PowerMod[Range[30], 2, 30]] (* Alonso del Arte, Nov 30 2019 *)

Scala

val squaresMod30 = (1 to 30).map(n => n * n).map(_ % 30)
(0 to 29).diff(squaresMod30) // Alonso del Arte, Nov 30 2019

Extensions

Incorrect term 15 removed by Alonso del Arte, Nov 30 2019