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

1,1

Links

Table of n, a(n) for n=1..48.

Example

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.

Mathematica

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

Prog

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

Crossrefs

Cf. A010421.

Sequence in context: A039251 A283296 A028797 * A028813 A158276 A028793

Adjacent sequences: A028770 A028771 A028772 * A028774 A028775 A028776

Keyword

nonn,fini,full,easy

Author

N. J. A. Sloane

Status

approved