A028773 Nonsquares mod 60.

2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 22, 23, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 46, 47, 48, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• fini
• full
• easy

Examples

			x^2 = 20 mod 60 has no solutions, so 20 is in the sequence.
x^2 = 21 mod 60 has the following solutions: x = 9, x = 21, x = 39, x = 51. Hence 21 is not in the sequence.
		

Crossrefs

Cf. A010421.

Programs

Mathematica

Complement[Range[59], PowerMod[Range[60], 2, 60]] (* Alonso del Arte, Jan 13 2017 *)

Scala

(0 to 59).diff((1 to 60).map(n => n * n % 60)) // Alonso del Arte, Jan 03 2020